Prepared exclusively for Richard Pokorny Transaction: 1929
Dr. Birdley Teaches Science!
Forces and Motion
Featuring the Comic Strip
Middle and High School
Innovative Resources for the Science Classroom
Written and Illustrated by Nevin Katz
Incentive Publications, Inc.
Nashville, Tennessee
Prepared exclusively for Richard Pokorny Transaction: 1929
About the Author
Nevin Katz is a teacher and curriculum developer who lives in Amherst, Massachusetts
with his wife Melissa and son Jeremy.
Nevin majored in Biology at Swarthmore College and went on to earn his Master’s
in Education at the Harvard Graduate School of Education. He began developing
curriculum as a student teacher in Roxbury, Massachusetts.
“Mr. Katz” has been teaching science for over seven years, in grades 6 through 11.
He currently teaches Environmental Science and Physical Science at Ludlow High
School in Ludlow, Massachusetts.
Nevin’s journey with Dr. Birdley and the cast began in the summer of 2002, when
he started authoring the cartoon and using it in his science classes. From there, he
developed the cartoon strip, characters, and curriculum materials. After designing and
implementing the materials, he decided to develop them further and organize them into
a series of books.
Cover by Geoffrey Brittingham
Edited by Jill Norris
Science Editors: K. Noel Freitas and Scott Norris
ISBN 978-0-86530-541-0
Copyright ©2008 by Incentive Publications, Inc., Nashville, TN. All Rights Reserved. The Dr. Birdley
comic strip and all characters depicted in the comic strips, Copyright ©2007 by Nevin Katz. All rights
reserved. The Dr. Birdley logo, Dr. BirdleyTM, JaykesTM, Dean OwelleTM, Professor BrockleyTM, Gina
SparrowTM, and all prominent characters featured in this publication are trademarks of Nevin Katz.
No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form
or by any means (electronic, mechanical, photocopying, or otherwise) without written permission from
Incentive Publications, with the exception below:
©
Pages labeled with the statement Copyright 2008 by Incentive Publications are intended for reproduction
within the owner’s classes. Permission is hereby granted to the purchaser of one copy of Forces and
Motion to reproduce these pages in sufficient quantities for meeting the purchaser’s classroom needs
only. Please include the copyright information at the bottom of each page on all copies.
1
2
3
4
5
6
7
8
9
10
11
10
09
08
PRINTED IN THE UNITED STATES OF AMERICA
www.incentivepublications.com
Prepared exclusively for Richard Pokorny Transaction: 1929
Table of Contents
Contents
Objectives and Frameworks .....................................2
Teacher’s Guide .......................................................5
Unit 1: Speed, Distance, and Time......................... 11
Unit 2: Velocity ......................................................19
Unit 3: Acceleration ...............................................29
Unit 4: Newton’s Law of Gravitation ....................39
Unit 5: Newton’s Laws of Motion .........................49
Unit 6: Force, Mass, and Acceleration ...................59
Unit 7: Motion in Two Dimensions .......................69
Unit 8: Disrupted Inertia ........................................79
Answer Key ...........................................................88
1
Prepared exclusively for Richard Pokorny Transaction: 1929
Educational Objectives
Central Goals:
• To explain and illustrate concepts of velocity, acceleration, force, and gravity
• To apply these ideas to real-life situations and connect them to Newton’s laws of
motion and gravitation
Chapter or Unit
Primary Objective(s)
Standards
1. Speed, Distance,
and Time
To calculate time, distance, and speed using mathematical formulas.
2. Velocity
To understand velocity as speed combined with direction.
1, 2
To represent changes in position using distance-time graphs
1, 2, 5
To calculate velocity using vectors and distance-time graphs.
3. Acceleration
To understand that acceleration can be a change in speed, direction, or both.
1, 5
To calculate acceleration and final velocity of moving objects.
4. Newton’s Law
of Gravitation
To apply Newton’s law of gravitation to planets and moons, as well as small
everyday objects.
10, 11
To illustrate how gravitational force is calculated.
5. Newton’s Laws
of Motion
To understand the major ideas behind Newton’s Laws.
3–9
To define force and explore the concept of net force.
To introduce the concepts of inertia and action-reaction force pairs.
To calculate force, mass, and acceleration using Newton’s second law.
6. Force, Mass, and
Acceleration
To learn how to calculate force, mass, and acceleration.
7. Motion in Two
Dimensions
To distinguish between the horizontal and vertical components of an object
in motion.
4, 6, 8
To understand how equal amounts of drag force and gravitational force result
in terminal velocity.
1, 5
To understand the independent nature of these two components.
To describe and illustrate how gravity and air resistance affect
projectile motion.
8. Inertia and
Friction
To understand how the law of inertia is applied to moving objects in real life. 3, 5
To understand how frictional forces can interferre wtih inertia.
Dr. Birdley Teaches Science – Forces and Motion
2
Prepared exclusively for Richard Pokorny Transaction: 1929
Relevant Frameworks
Motion & Forces, Grade 5-8
Motion & Forces Standards, Grades 9-12
1. The motion of an object can be described by its
position, direction of motion, and speed.
6. Objects change their motion only when a net
force is applied.
2. Motion can be measured and represented
on a graph.
7. Laws of motion are used to calculate precisely
the effects of forces on the motion of objects.
3. An object that is not being subjected to a force
will continue to move at a constant speed and in
a straight line.
8. The magnitude of the change in motion can be
calculated using the relationship F = ma, which
is independent of the nature of the force.
4. If more than one force acts on an object along
a straight line, then the forces will reinforce or
cancel one another, depending on their direction
and magnitude.
9. Whenever one object exerts force on another,
a force equal in magnitude and opposite in
direction is exerted on the first object.
10. Gravitation is a universal force that each
mass exerts on any other mass.
5. Unbalanced forces will cause changes in the
speed or direction of an object’s motion.
11. The strength of the gravitational attractive
force between two masses is proportional to
the masses and inversely proportional to the
square of the distance between them.
Dr. Birdley Teaches Science – Forces and Motion
3
Prepared exclusively for Richard Pokorny Transaction: 1929
Overview of Forces & Motion Source Cartoons
The difficulty level ranges from easy (L1) to very challenging (L3).
Cartoon
Central Concepts
Challenge
Level
Related Topics
Rollerblades
Representing speed on distance-time graphs
L1
Scientific Method
Data Analysis
Velocity in
Tennis
Velocity and vectors
L2
Projectile Motion
Acceleration
Vectors on
a River
Finding resultant velocity through vector
addition
L3
Pythagorean Theorem
Camel
Acceleration and deceleration
L1
Velocity
Science Sharks
Calculating final velocity of a falling object
L2
Acceleration Due to Gravity
Birdley Meets
Newton
Newton’s Law of Gravitation
L1
Newton’s Life
Gravitational
Force
The equation for gravitational force.
L3
Scientific Notation
Owelle Meets
Newton
Newton’s Three Laws Of Motion
L2
The Newton Balance
Tug-of-war
Balanced and unbalanced forces
L1
Friction
Baseball
Horizontal and vertical components of a
baseball’s trajectory
L2
Acceleration Due to Gravity
Hang Time
Horizontal and vertical components of
jumping
.
L2
Acceleration Due to Gravity
Initial and Final Velocity
Forces in
Hockey
Force, mass, and acceleration
L2
Friction
Terminal
Velocity
Drag force, gravity, and terminal velocity
L2
Balanced Forces
Net Force
Force and Acceleration
Inertia
The inertia of objects in motion
L2
Projectile Motion
The effect of friction on inertia
L1
Types of Friction
Friction in Golf
Dr. Birdley Teaches Science – Forces and Motion
4
Prepared exclusively for Richard Pokorny Transaction: 1929
Unit 1: Speed, Distance, and Time
Contents
Source Cartoon: Speed on a Graph 12
Cartoon Profile 13
Background 14
Study Questions 15
Visual Exercise 16
Vocabulary Build-up 17
Quiz 18
11
Prepared exclusively for Richard Pokorny Transaction: 1929
5
4
3
distance (km)
2
1
0
5
10
15
20
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
Copyright © 2007 by Nevin Katz
25
30
time (minutes)
35
40
45
50
Dr. Birdley Teaches Science – Forces and Motion
12
Prepared exclusively for Richard Pokorny Transaction: 1929
SPEED ON A GRAPH
Distance, Time, Speed
Objectives
1. To define speed as the amount of distance
an object travels over time
2. To show how speed is represented as the
slope of a line on a distance-time graph
3. To illustrate how distance-time graphs
indicate speed, as well as changes in speed
Synopsis
Owelle and Phyll begin by explaining the
definition of speed. They compare the speeds of
two model cars using a distance-time graph.
In the next scene, Dr. Birdley is jogging, while
Clarissa is rollerblading. Owelle then presents
a distance-time graph that illustrates changes in
their speed during the workout.
Main Ideas
1. Speed is the amount of distance an object
travels over time
2. On a distance-time graph, the speed of an
object is represented by the steepness of
the slope.
Questions for Discussion
3. Gradual slopes indicate low speed.
Before Reading:
4. Steep slopes indicate high speed.
1. How do you define speed?
5. A flat line on a distance-time graph
indicates a speed of zero.
2. What units are used to measure
distance? Time?
Vocabulary
distance
time
speed
y-axis
x-axis
slope
3. What different types of graphs might be
used to show data?
After Reading:
1. How does Dean Owelle define speed?
Characters
2. What is a slope?
Dean Owelle, Phyll, Dr. Birdley, Clarissa
3. Look at the panel where Clarissa speeds
up. What do you notice about the slope
of her line in the graph at that point?
Teacher’s Notes
Help students make the connection between the
panels on Clarissa’s movement and the graph.
The lines on the graph are in sync with the panels.
A problem-solving strategy for calculating slope is
featured in the background section.
Dr. Birdley Teaches Science – Forces and Motion
13
Prepared exclusively for Richard Pokorny Transaction: 1929
NAME: ______________________
SPEED, DISTANCE, AND TIME
BACKGROUND: SOLVING
CLASS: ________ DATE: ________
FOR
SPEED
The following procedure can be used to find the speed of a moving object.
A train travels a distance (d) of 500 meters in a time (t) of 50 seconds. What is the speed (s)?
1. Write out the formula you are using.
s = d / t.
2. Write down all your known quantities.
d = 500 m
t = 50 s.
3. Substitute these quantities into the equation.
s = 500 m / 50s
4. Solve.
s = 10 m/s
Directions: Solve the following problem to the best of your ability.
A dinosaur walks 600 meters in 30 seconds. What is its speed?
Pick two points with coordinates (x1, y1) and (x2, y2)
For example, points (2, 4) and (4, 8) on the graph to the right.
Then, plug the coordinates into the equation below;
slope (m) =
rise
run
=
(y2-y1)
(x2-x1)
=
(8-4)
(4-2)
=
4
2
= 2 meters/second
This method works for any other two points on this graph.
Distance (meters)
2 3 4 5 6 7 8 9 10
You can also find speed by finding the slope of a line on a graph.
Here is how you do it:
Distance-Time Graph
(4, 8)
(2, 4)
1
FINDING THE SLOPE OF A LINE
0
1
2
3
4
5
Time (seconds)
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
Dr. Birdley Teaches Science – Forces and Motion
14
Prepared exclusively for Richard Pokorny Transaction: 1929
NAME: ______________________
SPEED ON A GRAPH
CLASS: ________ DATE: ________
STUDY QUESTIONS
Directions: Answer the following questions to the best of your ability.
1. Look at the second panel in Speed on a Graph. How does the graph tell you
that car B is moving faster than car A?
_________________________________________________________
_________________________________________________________
2. According to the graph in the last panel, what is Owen‛s speed (in meters per
minute) over the first 15 minutes? How far does he travel?
________ _________________________________________________
_________________________________________________________
3. According to the graph, what is Clarissa‛s speed (in meters per minute)
between 15 and 25 minutes?
_________________________________________________________
_________________________________________________________
4. Do Owen and Clarissa reach their starting point at 50 minutes?__________
How do you know? ___________________________________________
_________________________________________________________
5. Owelle and Birdley run a road race, and their performance is recorded on a
distance-time graph. The slope of Birdley‛s line is steeper than Owelle‛s.
What does this mean?________________________________________
_________________________________________________________
Dr. Birdley Teaches Science – Forces and Motion
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
15
Prepared exclusively for Richard Pokorny Transaction: 1929
NAME: ______________________
DISTANCE-TIME GRAPH
CLASS: ________ DATE: ________
WORKOUT INFO
A. At this point, Clarissa stops.
B. Clarissa goes from a faster speed to
a slower speed.
C. Here, Clarissa goes from a slow speed to
a faster speed.
D. Clarissa changes direction a second time.
E. Clarissa starts moving again, this time in
the reverse direction.
F. Clarissa travels six meters at a steady speed.
3.___
2.___
4.__
6.___
1.___
5.__
0
Distance (in meters)
1 2 3 4 5 6
7
8
Distance Traveled by Clarissa Over Time
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
Time (seconds)
6. What is the slope of the line in the first three seconds?
7. What is Clarissa‛s speed between three and eight seconds? How do you know?
8. When does Clarissa reverse direction while maintaining a constant speed?
Dr. Birdley Teaches Science – Forces and Motion
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
16
Prepared exclusively for Richard Pokorny Transaction: 1929
SPEED, DISTANCE, AND TIME
NAME: ______________________
CLASS: ________ DATE: ________
VOCABULARY BUILD-UP
Directions: Read the definition and sample sentence. Then, write your own sample sentence
and draw a cartoon that illustrates speed.
Definition: Speed is the amount of distance covered per unit time.
Sample sentence: Clarissa Birdley‛s speed is the fastest in the middle of her workout, when
she is traveling at a speed of 15 m/s.
Give a sample sentence of your own that conveys the meaning of speed.
__________________________________________________________________
__________________________________________________________________
Draw a cartoon that illustrates the meaning of speed. Use words and pictures to convey
its definition.
Useful elements include:
word balloons and narration panels
fast and slow objects
characters, places, objects
someone measuring the speed of an object
numbers and formulas
tools used to measure speed
Dr. Birdley Teaches Science – Forces and Motion
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
17
Prepared exclusively for Richard Pokorny Transaction: 1929
Name:__________________________________ Class:_________ Date:____________
Unit 1 Quiz: Speed
Directions: Birdley is running on a soccer field to warm up for a race. Examine the graph of the
distance he travels below. Then, answer the related questions to the best of your ability.
c
d
f
b
e
a
0
Distance (in meters)
1 2 3 4 5 6
7
8
Distance Traveled by Birdley Over Time
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
Time (seconds)
4. Birdley is not moving between points
1. Birdley moves in the same direction and
increases his speed at
a and b
point e
b and c
point b
c and d
point c
d and e
point d
5. Birdley heads towards the starting location
between the points
2. Birdley reverses direction at the following points
a and c
a and b
e and d
b and c
b and d
c and d
b and f
d and e
6. Birdley stays in the same direction and slows
down at
3. From point b to point c, Birdley’s speed
(shown by the slope of the line) is equal to
0.4 m/s
point b
2.5 m/s
point d
10 m/s
point e
3.5 m/s
point f
Dr. Birdley Teaches Science – Forces and Motion
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
18
Prepared exclusively for Richard Pokorny Transaction: 1929
Unit 2: Velocity
Contents
Source Cartoon: Tennis & Velocity 20
Source Cartoon: Vectors on a River 21
Cartoon Profiles (2) 22
Study Questions (2) 24
Background 26
Visual Exercise 27
Vocabulary Build-up 28
19
Prepared exclusively for Richard Pokorny Transaction: 1929
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
Copyright © 2007 by Nevin Katz
Dr. Birdley Teaches Science – Forces and Motion
20
Prepared exclusively for Richard Pokorny Transaction: 1929
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
Copyright © 2007 by Nevin Katz
Dr. Birdley Teaches Science – Forces and Motion
21
Prepared exclusively for Richard Pokorny Transaction: 1929
TENNIS & VELOCITY
Velocity and Vectors
Objectives
1. To define and give examples of velocity.
2. To illustrate how velocity is represented
with vectors
3. To explain why velocity changes along a
curved paths.
Synopsis
Birdley and Norman are playing Jaykes and
Birdley’s dad in a game of tennis doubles. After
a couple of questions by Norman, Birdley begins
explaining the velocity of the tennis ball. As
Birdley finishes his explanations, Norman wins
the point with an overhead smash.
Main Ideas
1. Velocity describes the speed and direction
of an object.
2. Velocity vectors can be represented by
arrows, which have both direction
and magnitude.
3. If an object follows a curved path, velocity
is constantly changing because the object’s
direction is changing.
Questions for Discussion
Before Reading:
1. In tennis, how do you control the
speed and direction of the ball?
Vocabulary
velocity
vectors
speed
direction
2. How would you control the speed and
direction of a ball in another sport?
magnitude
3. What do you already know
about speed?
Characters
Dr. Birdley, Jaykes, Norman, Birdley’s dad
After Reading:
Teacher’s Notes
1. What was the direction of
Norman’s ball?
Draw the multiple vectors of a curved path to
show how it is different from a straight path. One
example is the vector breakdown of this ball’s
trajectory:
2. How could vectors be used to represent
the curved path of a tennis ball?
3. How is velocity different from speed?
Dr. Birdley Teaches Science – Forces and Motion
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
22
Prepared exclusively for Richard Pokorny Transaction: 1929
VECTORS ON A RIVER
Vector Addition
Objectives
1. To illustrate how a problem involving two
components to velocity can be solved using
vector addition.
2. To illustrate the steps of the
Pythagorean Theorem.
Synopsis
Dr. Birdley and Dean Owelle are paddling
their canoe along a river. As Birdley begins to
philosophize, Owelle notices that they are headed
toward the waterfall. After they turn the boat
toward the riverbank, Birdley attempts to calculate
the resultant velocity of the boat through vector
addition. The solution to the problem is below
and in this unit’s background section.
Main Ideas
1. Vectors represent speed and direction.
2. To find the resultant velocity of a boat on
a river, the velocity of the boat itself and the
velocity of the river flow must be taken
into account.
Questions for Discussion
3. Resultant velocity can be found using vector
addition.
Before Reading:
4. For problems involving two perpendicular
velocities, resultant velocity can be found
using the Pythagorean Theorem where a, b,
and c are three sides of a right triangle and c
is the unknown velocity:
a = 4 m/s
b = 3 m/s
c=?
1. If you are traveling by canoe, why is it
easier to go with the flow of a river?
2. What happens if you go against the
flow? Why?
3. If you are going with the flow of a river,
what would happen to the boat if you
paddled directly toward a riverbank?
a2 + b2 = c2
42 + 32 = c2
16 + 9 = 25 = c2
c=
c2 =
After Reading:
25 = 5
1. Did Birdley finish the problem by the
time Owelle jumped off the boat?
Vocabulary
vectors
velocity
hypotenuse
Pythagorean Theorem
2. What steps are left for solving the
problem? Go through them?
vector addition
Characters
Dr. Birdley, Dean Owelle
Dr. Birdley Teaches Science – Forces and Motion
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
23
Prepared exclusively for Richard Pokorny Transaction: 1929
NAME: ______________________
TENNIS & VELOCITY
CLASS: ________ DATE: ________
STUDY QUESTIONS
Directions: Answer the following questions to the best of your ability.
1. Suppose a tennis ball is flying through the air at 70 mph. Does this
statement describe the tennis ball‛s velocity? Why or why not?
_________________________________________________________
_________________________________________________________
2. Write a statement that describes the velocity of a moving object.
_________________________________________________________
_________________________________________________________
3. Suppose a roller coaster car is moving in a curved path at a steady speed of
60 mph. Is it changing velocity? How do you know?
_________________________________________________________
_________________________________________________________
4. List three events in a tennis game that would change the velocity of the ball.
_________________________________________________________
_________________________________________________________
5. Suppose Norman‛s backhand sends the ball flying with a starting velocity of
75 mph east. Could the wind affect the velocity of the ball? Explain.
_________________________________________________________
_________________________________________________________
Dr. Birdley Teaches Science – Forces and Motion
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
24
Prepared exclusively for Richard Pokorny Transaction: 1929
NAME: ______________________
VECTORS ON A RIVER
CLASS: ________ DATE: ________
STUDY QUESTIONS
Directions: Answer the following questions to the best of your ability.
1. In what direction is the boat headed at the beginning of the comic?
What causes the boat to change its velocity?
_________________________________________________________
_________________________________________________________
2. Describe the general direction of the boat after Birdley and Owelle steer it
toward the riverbank. Use the compass shown in the comic.
_________________________________________________________
_________________________________________________________
3. As Birdley and Owelle paddle toward the riverbank, what two factors affect
the boat‛s velocity?
_________________________________________________________
_________________________________________________________
4. Why does Birdley use the Pythagorean Theorem?
_________________________________________________________
_________________________________________________________
5. What is the boat‛s resultant velocity? (Hint: Use the Pythagorean Theorem
to find the length of the triangle‛s longest side.)
_________________________________________________________
_________________________________________________________
Dr. Birdley Teaches Science – Forces and Motion
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
25
Prepared exclusively for Richard Pokorny Transaction: 1929
NAME: ______________________
VECTOR ADDITION
CLASS: ________ DATE: ________
BACKGROUND: PYTHAGOREAN THEOREM
AND
VECTORS
If a vehicle‛s velocity has two perpendicular components, you can use the Pythagorean Theorem to find the
resultant velocity. This procedure shows you how.
3 m/s
a = 4 m/s
4 m/s
1. Draw the two perpendicular velocities as
vectors, oriented head to tail.
2. Draw the resultant vector so that you
form a right triangle.
3. Set up the pythagorean equation.
4. “Plug in” your known quantities.
b = 3 m/s
c=?
a2 + b2 = c2
4
2
+ 32 = c2
5. Multiply exponents.
16 + 9 = c2
6. Add.
25 = c2
7. Find the square root of c.
c =
c2 =
25 = 5 m/s
northeast
Directions: Solve the following problem to the best of your ability.
1. A boat is sailing north at 24 m/s. The river is flowing east and 18 m/s. Draw a diagram and use the
Pythagorean Theorem to find final velocity.
Dr. Birdley Teaches Science – Forces and Motion
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
26
Prepared exclusively for Richard Pokorny Transaction: 1929
NAME: ______________________
VECTOR ADDITION
CLASS: ________ DATE: ________
a = 4 m/s
Pythagorean Theorem:
a2 + b2 = c2
b = 3 m/s
c=?
2
2
2
4 +3 =c
16 + 9 = 25 = c2
c = c2 =
river:
100 = 10
river: 9 m/s,
30 m/s, east
northwest
boat:
40 m/s,
boat: 12 m/s,
north
northeast
1. Resultant velocity of boat: _____
2. Resultant velocity of boat: _____
river:
20 m/s, west
river:
boat:
15 m/s,
north
16 m/s,
north
boat:
12 m/s, east
4. Resultant velocity of boat: _____
3. Resultant velocity of boat: _____
Dr. Birdley Teaches Science – Forces and Motion
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
27
Prepared exclusively for Richard Pokorny Transaction: 1929
NAME: ______________________
VELOCITY AND VECTORS
CLASS: ________ DATE: ________
VOCABULARY BUILD-UP
Directions: Read the definition and sample sentence. Then, write your own sample sentence
and draw a cartoon that illustrates velocity.
Definition: Velocity is a quantity that describes speed and direction.
Sample sentence: The velocity of the golf ball is 10 m/s northeast.
10 m/s, NE
Give a sample sentence of your own that conveys the meaning of velocity.
_________________________________________________________
_________________________________________________________
Draw a cartoon that illustrates the meaning of velocity. Include some of thse elements:
word balloons and narration panels
characters, places, objects,
numbers, vectors, and formulas
Dr. Birdley Teaches Science – Forces and Motion
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
28
Prepared exclusively for Richard Pokorny Transaction: 1929
Unit 3: Acceleration
Contents
Source Cartoon: The Camel 30
Source Cartoon: Science Sharks 31
Cartoon Profiles (2) 32
Study Questions (2) 34
Background 36
Visual Exercise 37
Vocabulary Build-up 38
Quiz 39
29
Prepared exclusively for Richard Pokorny Transaction: 1929
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
Copyright © 2007 by Nevin Katz
Dr. Birdley Teaches Science – Forces and Motion
30
Prepared exclusively for Richard Pokorny Transaction: 1929
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
Copyright © 2007 by Nevin Katz
Dr. Birdley Teaches Science – Forces and Motion
31
Prepared exclusively for Richard Pokorny Transaction: 1929
THE CAMEL
Acceleration
Objectives
1. To define acceleration in relation to velocity.
2. To illustrate the circumstances under which
an object accelerates.
Synopsis
As Birdley rides a camel through the desert,
he teaches a lesson on acceleration. The camel
accelerates in various ways to illustrate
this concept.
Main Ideas
1. Acceleration always involves a change in
velocity over time.
2. When an object’s speed increases, it covers
more distance per unit time with every
passing second.
3. Acceleration can involve a change in speed,
direction, or both.
4. When an object decelerates, it slows down.
Questions for Discussion
Vocabulary
acceleration
velocity
speed
direction
time
distance
Before Reading:
1. What does a car do when it accelerates?
2. Does a rollercoaster accelerate?
If so, when?
Characters
3. How could you change velocity when
you are walking?
Dr. Birdley, desert cop, camels
Teacher’s Notes
After Reading:
1. What does it mean to decelerate?
The comic and study questions set you up to
introduce this equation for finding acceleration:
2. Look at the third (long) panel in the
comic. What happens over time to the
amount of distance the camel covers
per second? Why?
vf = vi + (a x t)
a = acceleration
t = time
vi= initial velocity
vf = final velocity
3. Based on the comic, what do you think
it means to decelerate?
Dr. Birdley Teaches Science – Forces and Motion
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
32
Prepared exclusively for Richard Pokorny Transaction: 1929
SCIENCE SHARKS
Acceleration and Gravity
Objectives
1. To provide an example of acceleration
due to gravity.
2. To illustrate the steps for solving for final
velocity using time, acceleration, and
initial velocity.
Synopsis
From the deck of a ship, Dr. Birdley drops a rock
into the water. Two of the science sharks use the
information, gather information about the drop,
and calculate the rock’s final velocity just before
it hits the water.
Main Ideas
1. Before solving a problem, write out the
formula you are using. In this case,
vf = vi + (a x t).
2. Use the information in the situation to write
down all your known quantities. Include
units. In this case, you have:
vi = initialy velocity = 0 m/s
Questions for Discussion
t = time = 2 s.
Before Reading:
a = acceleration = 9.8 m/s2
1. What happens to the speed of a falling
object? Why?
3. Substitute these quantities into the equation
and you have:
2. What do you need to know in order
to find an object’s acceleration?
Final velocity?
vf = 0 m/s + (9.8 m/s2 x 2 s)
4. Solve. vf = 19.6 m/s
5. If an object is dropped, it accelerates due
to gravity. The more time it has to fall, the
greater its final velocity is just before impact.
3. What determines how long it takes for
something to fall?
4. What determines the speed of a
falling object?
Vocabulary
acceleration
time
initial velocity
equation
variable
final velocity
knowns
unknowns
gravity
After Reading:
1. Suppose Birdley drops the rock from a
lower point. How would this affect the
rock’s final velocity?
Characters
2. How did the sharks calculate the rock’s
final velocity?
Dr. Birdley and the Science Sharks
Dr. Birdley Teaches Science – Forces and Motion
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
33
Prepared exclusively for Richard Pokorny Transaction: 1929
NAME: ______________________
THE CAMEL
CLASS: ________ DATE: ________
STUDY QUESTIONS
Directions: Answer the following questions to the best of your ability.
1. How does acceleration relate to velocity?
_________________________________________________________
_________________________________________________________
2. Suppose a camel heading north remains at the same speed but then changes
its direction towards the east. Does it accelerate? Why or why not?
_________________________________________________________
_________________________________________________________
3. A camel with an initial velocity of 10 m/s starts to accelerate at 5 m/s2
for five seconds. What is the camel‛s final velocity? Show your work.
_________________________________________________________
_________________________________________________________
4. A camel speeds up, maintains the same speed for ten seconds, and then gets
tired and slows down. When is the camel decelerating? Why?
_________________________________________________________
_________________________________________________________
5. How does Dr. Birdley‛s camel end up speeding? Use the term “accelerate” or
“acceleration” in your answer.
_________________________________________________________
_________________________________________________________
Dr. Birdley Teaches Science – Forces and Motion
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
34
Prepared exclusively for Richard Pokorny Transaction: 1929
NAME: ______________________
SCIENCE SHARKS
CLASS: ________ DATE: ________
STUDY QUESTIONS
Directions: Answer the following questions to the best of your ability.
1. What are the sharks trying to find? What information did the sharks
gather through observation?
_________________________________________________________
_________________________________________________________
2. What information did the sharks write down before solving the problem?
What equation did they use?
_________________________________________________________
_________________________________________________________
3. Suppose Birdley were to attach a parachute to the rock he drops.
How would this affect the rock‛s final velocity? Why?
_________________________________________________________
_________________________________________________________
If
4. Another rock is dropped from a higher point and falls for 5 seconds before
hitting the ground. Assuming acceleration due to gravity is 9.8 m/s2, what is
the rock‛s final velocity the instant before it hits the ground?
_________________________________________________________
_________________________________________________________
5. How will the rock accelerate or decelerate when it hits the water? Why?
_________________________________________________________
_________________________________________________________
Dr. Birdley Teaches Science – Forces and Motion
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
35
Prepared exclusively for Richard Pokorny Transaction: 1929
NAME: ______________________
ACCELERATION
BACKGROUND: PROCEDURE
CLASS: ________ DATE: ________
FOR
FINDING FINAL VELOCITY
Use the following procedure to solve for the final velocity of a moving object that is accelerating.
vf = final velocity, vi = initial velocity, a = acceleration, and t = time.
vf = vi + (a x t).
1. Write out the formula you are using.
vi = 0 m/s
2. Write down all your known quantities.
t = 2 s.
a = 9.8 m/s2
3. Substitute these quantities into the equation.
vf = 0 m/s + (9.8 m/s2 x 2 s)
4. Solve.
vf = 19.6 m/s
Directions: Solve the following problems to the best of your ability.
1. A resting object is dropped, and falls for six seconds before hitting the ground. Assuming that acceleration
due to gravity is 9.8 m/s2, find its final velocity before impact.
2. A car initially going at 30 m/s accelerates by 5 m/s2. Find the car‛s velocity after it has accelerated for
seven seconds.
Dr. Birdley Teaches Science – Forces and Motion
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
36
Prepared exclusively for Richard Pokorny Transaction: 1929
NAME: ______________________
ACCELERATION EQUATIONS
CLASS: ________ DATE: ________
2.
1.
4.
3.
Dr. Birdley Teaches Science – Forces and Motion
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
37
Prepared exclusively for Richard Pokorny Transaction: 1929
Name:__________________________________ Class:_________ Date:____________
Unit 3 Quiz: Acceleration
Directions: This quiz tests your knowledge of the chapter’s cartoon, background article, and visual
exercises. Answer the following questions to the best of your ability.
1. Acceleration always involves a change in
4. A rock is dropped from rest and falls for four
seconds before hitting the ground. Assuming
acceleration due to gravity is 9.8 m/s2, what
is the rock’s final velocity the instant before it
hits the ground?
speed
velocity
direction
gravity
2
39.2 m/s
19.6 m/s2
2. If a truck decelerates, it always
13.8 m/s2
speeds up
5.8 m/s2
maintains a constant speed
slows down
5. A box is falling with a downward velocity of
10 m/s. It falls for two more seconds before
hitting the water. Assuming acceleration due
to gravity is 9.8 m/s2, what is the box’s final
velocity before hitting the water?
comes to a complete stop
3. A car traveling at a speed of 30 m/s changes
speed to 50 m/s over four seconds. What is
the car’s acceleration?
19.8 m/s2
80 m/s2
29.6 m/s2
20 m/s2
9.6 m/s2
12.5 m/s2
29.8 m/s2
5 m/s2
6. A person walking at 2 m/s changes direction but still continues walking at the same speed. Is this
person accelerating? Why or why not?
______________________________________________________________
______________________________________________________________
______________________________________________________________
7. A cyclist starting from rest accelerates at a rate of 6 m/s2 until she reaches 30 m/s. How long
does it take her to accelerate? (Hint: re-arrrange your equation for acceleration so that you solve
for time.)
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
Dr. Birdley Teaches Science – Forces and Motion
38
Prepared exclusively for Richard Pokorny Transaction: 1929
Unit 5: Newton’s Laws of Motion
Contents
Source Cartoon: Owelle meets Newton 50
Source Cartoon: Tug of War 51
Cartoon Profiles (2) 52
Study Questions (2) 54
Mini-Comic: Action-Reaction Pairs 56
Visual Exercise 57
Vocabulary Build-up 58
49
Prepared exclusively for Richard Pokorny Transaction: 1929
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
Copyright © 2007 by Nevin Katz
Dr. Birdley Teaches Science – Forces and Motion
50
Prepared exclusively for Richard Pokorny Transaction: 1929
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
Copyright © 2007 by Nevin Katz
Dr. Birdley Teaches Science – Forces and Motion
51
Prepared exclusively for Richard Pokorny Transaction: 1929
OWELLE MEETS NEWTON
Laws of Motion
Objectives
1. To introduce Newton’s three laws of motion.
2. To introduce the Newton balance, which
measures force in Newtons.
Synopsis
After bringing Newton to the present, Birdley
introduces him to Dean Owelle, who doubts the
great scientist’s true identity. Newton proves his
identity by explaining his three laws of motion.
As he explains them, Jaykes provides examples of
the three laws using his lab equipment.
Main Ideas
1. An object at rest tends to stay at rest, and
an object in motion tends to stay in motion,
unless acted upon by an outside force.
2. The force exerted on an object is equal to its
mass multiplied by its acceleration. (F = ma)
3. Every action results in an equal and
opposite reaction.
Vocabulary
Questions for Discussion
force
action
reaction
Newton (N)
Newton meter
inertia
mass
acceleration
Before Reading:
1. What do you know so far about
Sir Isaac Newton?
2. What is a force?
3. What do you already know
about gravity?
Characters
Dr. Birdley, Sir Isaac Newton, Jaykes,
Dean Owelle, Norman
After Reading:
1. What were Newton’s three laws?
2. If you were Owelle, would you be
convinced that the guy is Newton?
Why or why not?
Teacher’s Note
The comic sets you up to introduce the term
inertia. Prior to introducing the comic, it helps
for students to be familiar with air resistance
and friction, which also disrupt the ball’s inertia
(referred to in study question #2, p. 54).
3. What does Norman do
to the ball’s inertia?
Dr. Birdley Teaches Science – Forces and Motion
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
52
Prepared exclusively for Richard Pokorny Transaction: 1929
TUG OF WAR
Net Force
Objectives
1. To introduce the Newton as the unit for force.
2. To compare and contrast balanced and
unbalanced forces.
3. To introduce the concept of net force.
Synopsis
Dr. Birdley uses a tug-of-war match to explain
the concept of balanced forces. Norman pulls
the rope on one end, creating a net force in his
direction. Don advises two students to restore
balance to the tug-of-war match.
Main Ideas
1. Force is measured in Newtons.
2. When two forces are equal and opposite in
direction, the net force is zero and there is
no acceleration.
3. In the tug-of-war match, the two opposing
forces create tension at the center of the rope.
4. If a force in one direction is greater than the
force in the opposite direction, then there is a
net force, resulting in movement.
Questions for Discussion
Before Reading:
1. What happens in a tug-of-war match?
Vocabulary
net force
Newton
balanced
2. How does someone win a tug-of-war
match?
unbalanced
Characters
After Reading:
Dr. Birdley, Dean Owelle, Jaykes, Gina, Lark,
Norman, Don, Anthony, Christina
1. Why did Jaykes and Owelle
start moving?
2. What could the students do to restore
balance to the tug-of-war match?
Teacher’s Notes
Question #3 involves the use of friction, so it
would be useful to touch on friction with your
students before using the comic. In this case,
Jaykes and Owelle dig their feet into the ground to
create friction that opposes their forward motion.
3. How did net force change during
the comic?
Dr. Birdley Teaches Science – Forces and Motion
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
53
Prepared exclusively for Richard Pokorny Transaction: 1929
NAME: ______________________
OWELLE MEETS NEWTON
CLASS: ________ DATE: ________
STUDY QUESTIONS
Directions: Answer the following questions to the best of your ability.
1. Based on Norman‛s comment, how would you define inertia?
_________________________________________________________
_________________________________________________________
2. Suppose the surface is not totally smooth. What additional “outside force”
would be affecting the ball‛s motion? How would its motion be affected?
_________________________________________________________
_________________________________________________________
3. How is Jaykes measuring the amount of force he uses to pull the weight?
What are the two other properties that relate to force?
_________________________________________________________
_________________________________________________________
4. How does the Newton meter demonstrate the law of action and reaction?
_________________________________________________________
_________________________________________________________
5. If Jaykes causes a 0.5 kg weight to accelerate by 5 m/s2, what force is
Jaykes using to pull the weight? Assume the weight is on a frictionless
surface. Use the equation he‛s thinking of.
_________________________________________________________
_________________________________________________________
Dr. Birdley Teaches Science – Forces and Motion
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
54
Prepared exclusively for Richard Pokorny Transaction: 1929
NAME: ______________________
TUG-OF-WAR
CLASS: ________ DATE: ________
STUDY QUESTIONS
Directions: Answer the following questions to the best of your ability.
1. When do two forces result in no motion?
_________________________________________________________
_________________________________________________________
2. In the comic, what causes the forces to become imbalanced? What is the
net force in this case?
_________________________________________________________
_________________________________________________________
3. What are Jaykes and Owelle doing to resist being pulled any further?
What principle of physics are they using?
_________________________________________________________
_________________________________________________________
If
4. How could Anthony and Christine restore balance to the tug-of-war match?
_________________________________________________________
_________________________________________________________
5. If Gina and Owelle were to compete by themselves in a tug-of-war match
and use the same force as in this comic, who would win? What would be the
net force?
_________________________________________________________
_________________________________________________________
Dr. Birdley Teaches Science – Forces and Motion
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
55
Prepared exclusively for Richard Pokorny Transaction: 1929
Newton‛s Law states that every action results in an equal and opposite reaction. For example, as Dr. Birdley‛s
weight pushes down on a bridge, a sturdy bridge will push back up on Dr. Birdley. This can be illustrated using
a force pair diagram, where arrows represent the directions of the forces at work (see above).
After the bridge breaks, the force pairs change.
The earth is pulling down on Owelle, while Owelle is
pulling up on the earth (see below.)
Action-reaction pairs can also be horizontal.
Here, as Dr. Birdley pushes on the cabinet, the
cabinet pushes back on him.
Draw the arrows here to
represent the pair of
forces at work.
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
Copyright © 2007 by Nevin Katz
Dr. Birdley Teaches Science – Forces and Motion
56
Prepared exclusively for Richard Pokorny Transaction: 1929
NAME: ______________________
ACTION / REACTION PAIRS
CLASS: ________ DATE: ________
Dr. Birdley Teaches Science – Forces and Motion
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
57
Prepared exclusively for Richard Pokorny Transaction: 1929
NAME: ______________________
FORCE
CLASS: ________ DATE: ________
VOCABULARY BUILD-UP
Directions: Read the definition and sample sentence. Then, write your own sample sentence
and draw a cartoon that illustrates velocity.
Definition: A force is defined as a push or a pull on an object.
Sample sentence: Norman pulled the rope with a force of 30 Newtons.
Give a sample sentence of your own that conveys the meaning of force.
_________________________________________________________
_________________________________________________________
Draw a cartoon that illustrates the meaning of force. Useful elements include:
word balloons and narration panels
characters, places, objects,
numbers and formulas
arrows with labels that indicate specific amounts of force (ex. F = 40 N)
Dr. Birdley Teaches Science – Forces and Motion
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
58
Prepared exclusively for Richard Pokorny Transaction: 1929
Unit 6: Force, Mass, and Acceleration
Source Cartoon: Forces in Hockey 60
Source Cartoon: Terminal Velocity 61
Cartoon Profiles (2) 62
Study Questions (2) 64
Visual Exercise 66
Quiz 67
Reference Sheet: Key Formulas 68
59
Prepared exclusively for Richard Pokorny Transaction: 1929
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
Copyright © 2007 by Nevin Katz
Dr. Birdley Teaches Science – Forces and Motion
60
Prepared exclusively for Richard Pokorny Transaction: 1929
t=0
v = 0 m/s
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
Copyright © 2007 by Nevin Katz
Dr. Birdley Teaches Science – Forces and Motion
61
Prepared exclusively for Richard Pokorny Transaction: 1929
FORCES IN HOCKEY
Newton’s Second Law
Objectives
1. To illustrate how the equation F = ma applies
to hockey.
2. To show how to rearrange the variables in
the equation to solve for acceleration.
3. To show the relationship between force
and acceleration.
4. To show how mass and acceleration
are related.
5. To pair equations with action sequences that
students can readily understand.
Synopsis
While coaching hockey practice, Dr. Birdley
explains how Newton’s second law (F = m x a)
applies to ice hockey.
Main Ideas
1. Force is equal to the mass of an object
multiplied by its acceleration (F = m x a).
2. Acceleration is equal to the force exerted on
an object divided by mass. (a = F/m).
Questions for Discussion
3. In other words, the greater an object’s mass,
the less it will accelerate given an equal
amount of force.
Before Reading:
1. What do we know so far about force?
mass? acceleration?
4. Increasing the amount of force you use on an
object will increase the object’s acceleration.
2. If you slide an object across your desk,
how can you control how far it goes?
How fast it goes ?
Vocabulary
force
acceleration
mass
units
kilograms
Newtons
After Reading:
1. How are the characters able to control
the speed of the hockey puck?
Characters
2. What is the large hockey puck’s
acceleration?
Dr. Birdley, Shelly, Neil, Anthony
3. Why does this hockey puck
accelerate less?
Teacher’s Note
The acceleration of the large puck in the final
panel is 3 m/s2.
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
62
Dr. Birdley Teaches Science – Forces and Motion
Prepared exclusively for Richard Pokorny Transaction: 1929
Gravity and Net Force
TERMINAL VELOCITY
Objectives
1. To connect gravity to the formula a = F/m.
2. To discuss the connection between air
resistance and terminal velocity.
Synopsis
As Dr. Birdley goes skydiving, he explains
how he reaches terminal velocity. He opens his
parachute to slow his fall, but gets stuck in a tree
on the way down.
Main Ideas
1. Before reaching terminal velocity, Birdley
accelerates due to gravity.
2. The other force at work is drag force, which
is caused by air resistance.
3. As Birdley speeds up, drag force increases.
This is because drag force is proportional to
the square of an object’s speed.
4. Birdley reaches terminal velocity when the
downward force of gravity is equal to the
upward force of drag.
Questions for Discussion
5. At this point, drag force cancels the force
of gravity, resulting in zero downward
acceleration. In terms of Newton’s formula,
(a = F/m), here is what happens to net force:
Before Reading:
1. Suppose you are skydiving. What
happens to your velocity / speed as
you fall?
F
F g - Fd
a = m =
= 0
m
2. How do parachutes work?
where Fg = force of gravity and Fd = force of drag
3. How do you think air resistance affects
your fall?
6. Because of its shape, the parachute increases
the amount of drag Birdley experiences and
lowers Birdley’s terminal velocity dramatically.
After Reading:
1. When does terminal velocity happen in
the comic?
Vocabulary
terminal velocity
gravity
acceleration
air resistance
drag
free fall
2. Why does Dr. Birdley’s parachute
slow his fall?
3. Why does Dr. Birdley stop accelerating?
Characters
Dr. Birdley and Detective Eggs Benedict
Dr. Birdley Teaches Science – Forces and Motion
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
63
Prepared exclusively for Richard Pokorny Transaction: 1929
NAME: ______________________
FORCES IN HOCKEY
CLASS: ________ DATE: ________
STUDY QUESTIONS
Directions: Answer the following questions to the best of your ability.
1. Translate the equation F = ma into a sentence.
_________________________________________________________
_________________________________________________________
2. How does the amount of force you use affect the acceleration of a hockey
puck?
_________________________________________________________
_________________________________________________________
3. Suppose you push two boxes with a force of 5 N. One box has a mass of 1 kg
and one box has a mass of 2 kg. Which box will speed up faster? Why?
_________________________________________________________
_________________________________________________________
4. After being hit with a hockey stick, a .20 kg puck accelerates at 50 m/s2.
What is the amount of force exerted on the puck?
_________________________________________________________
_________________________________________________________
5. Let‛s say 25 N of force are exerted on the .25 kg puck. What is the puck‛s
acceleration?
_________________________________________________________
_________________________________________________________
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
64
Dr. Birdley Teaches Science – Forces and Motion
Prepared exclusively for Richard Pokorny Transaction: 1929
NAME: ______________________
TERMINAL VELOCITY
CLASS: ________ DATE: ________
STUDY QUESTIONS
Directions: Answer the following questions to the best of your ability.
1. What happens to Dr. Birdley‛s velocity over the first several seconds? Why?
_________________________________________________________
_________________________________________________________
2. What force does force of drag oppose? What happens to force of drag as
velocity increases?
_________________________________________________________
_________________________________________________________
3. Compare force of drag and gravitational force once Birdley reaches terminal
velocity. What is the resulting net force?
_________________________________________________________
_________________________________________________________
4. What happens to Birdley‛s acceleration at terminal velocity? Why?
(Hint: what is the net force that results from drag opposing gravity?
How are force and acceleration related?)
_________________________________________________________
_________________________________________________________
5. Does the parachute increase or decrease Dr. Birdley‛s terminal velocity?
How? Explain your answer.
_________________________________________________________
_________________________________________________________
Dr. Birdley Teaches Science – Forces and Motion
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
65
Prepared exclusively for Richard Pokorny Transaction: 1929
FORCE, MASS, AND ACCELERATION
NAME: ______________________
CLASS: ________ DATE: ________
Dr. Birdley Teaches Science – Forces and Motion
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
66
Prepared exclusively for Richard Pokorny Transaction: 1929
Name:__________________________________ Class:_________ Date:____________
Unit 6 Quiz: Newton’s Laws of Motion
Directions: This quiz tests your knowledge of the cartoons, mini-comics, and visual exercises from
units 5 and 6. Answer the following questions to the best of your ability.
1. A .15 kg hockey puck, starting at rest, is
pushed so that it accelerates by 50 m/s2.
What is the force exerted on the puck?
4. At terminal velocity, a skydiver stops
accelerating because the ______ acting on
her becomes to zero.
50.15 N
gravitational force
330 N
force of drag
7.5 N
net force
49.85 N
the mass
2. If an object is in motion, and there are no
outside forces acting on it, the object’s
speed will
5. If only two equal yet opposing forces are
pushing on an object, the net force is always
zero
eventually reach 0 m/s
positive
remain the same
negative
increase over time
constantly changing
decrease over time
6. An object is in inertia if it
3. You push down on a table with your hands,
and the table does not break. The table is
has no net forces acting on it.
gets pushed or pulled
not pushing back at all
is accelerating
pushing down in the same direction
is falling
pushing sideways
pushing back up on your hands with
equal force
7. A person is standing on a bridge. Identify the two opposing forces at work in the space below.
Then, draw a diagram of the situation. Use arrows to illustrate the two opposing forces.
Action Force:____________________
Diagram:
_______________________________
Reaction Force:__________________
_______________________________
Dr. Birdley Teaches Science – Forces and Motion
67
Prepared exclusively for Richard Pokorny Transaction: 1929
NAME: ______________________
FORCES & MOTION
CLASS: ________ DATE: ________
Reference Sheet: Key Formulas
Directions: In each box, write the correct formula that is used to find the property
that is listed.
Speed, Time,
Accleration, Time,
and Distance
and Velocity
Force, Mass,
Acceleration, and
Gravitation
Speed (s)
acceleration (a)
Force (F)
Time (t)
time (t)
acceleration (a)
distance (d)
final velocity (vf)
mass (m):
slope (m)
deceleration (d)
Gravitational Force (Fg)
m = rise / run
*This slope formula would use two points on a line graph, with coordinates (x1, y1) and (x2, y2).
Dr. Birdley Teaches Science – Forces and Motion
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
68
Prepared exclusively for Richard Pokorny Transaction: 1929
Unit 8: Disrupted Inertia
Source Cartoon: Inertia 80
Source Cartoon: Friction in Golf 81
Cartoon Profiles (2) 82
Study Questions (2) 84
Visual Exercise 86
Mini-Comic 87
79
Prepared exclusively for Richard Pokorny Transaction: 1929
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
Copyright © 2007 by Nevin Katz
Dr. Birdley Teaches Science – Forces and Motion
80
Prepared exclusively for Richard Pokorny Transaction: 1929
IT‛S INERTIA
Laws of Motion
Objectives
1. To show that an object is in inertia if no
forces are acting on it.
2. To illustrate that an object in inertia could
still be in motion.
3. To practice breaking up an object’s motion
into horizontal and vertical components.
Synopsis
Neil, looking the other way while riding on a
skateboard, hits a fire hydrant and goes flying.
Birdley explains to him that he remained in inertia
while the skateboard was stopped by the
fire hydrant.
Main Ideas
1. Objects in motion can be in inertia.
2. As Neil hit the fire hydrant, he kept going
forward at the same velocity because no
horizontal forces were acting on him.
3. Although Neil’s horizontal velocity remained
the same, his vertical velocity changed
somewhat: first due to the upward push of the
skateboard, and then due to gravity.
Questions for Discussion
Before Reading:
1. Suppose I have an object on a
frictionless surface that extends
infinitely in all directions. What
happens if I give that object one push?
Vocabulary
inertia
force
velocity
2. Will it eventually stop? Or will it keep
going forever? If so, why?
Characters
3. Suppose you leave a soda can on the
top of a car and it takes off. What
would happen to the soda can if the car
were to suddenly come to a halt?
Dr. Birdley, Neil
Teacher’s Notes
Before reading this comic, it is helpful for
students to be familiar with the horizontal and
vertical components of velocity. This is covered
in the previous unit. Neil’s flight path is similar to
that seen in projectile motion. Try relating Neil
to other passengers on moving vehicles that
stop suddenly.
After Reading:
1. What happens to Neil?
2. Why does Neil remain in inertia?
3. What do seatbelts do if your car
suddenly stops? How does this relate
to inertia?
Dr. Birdley Teaches Science – Forces and Motion
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
82
Prepared exclusively for Richard Pokorny Transaction: 1929
NAME: ______________________
IT‛S INERTIA
CLASS: ________ DATE: ________
STUDY QUESTIONS
Directions: Answer the following questions to the best of your ability.
1. As his skateboard hits the fire hydrant, why does Neil continue to fly
forward? Explain.
_________________________________________________________
_________________________________________________________
2. Describe Neil‛s vertical motion in the comic.
_________________________________________________________
_________________________________________________________
3. What forces act on Neil‛s vertical motion?
_________________________________________________________
_________________________________________________________
4. Does the skateboard remain in inertia throughout the comic?
Why or why not?
_________________________________________________________
_________________________________________________________
5. How does inertia contribute to Neil‛s accident?
_________________________________________________________
_________________________________________________________
Dr. Birdley Teaches Science – Forces and Motion
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
84
Prepared exclusively for Richard Pokorny Transaction: 1929
1. Why does a lead weight fall faster than a feather?
2. Why would two objects fall at the same speed in a vacuum tube?
3. Two objects with different shapes fall at the same speed in open air. What can you
conclude about the amount of air resistance each object encounters?
Copyright © 2008 by Incentive Publications, Inc., Nashville, TN
Copyright © 2007 by Nevin Katz
Dr. Birdley Teaches Science – Forces and Motion
87
Prepared exclusively for Richard Pokorny Transaction: 1929
Prepared exclusively for Richard Pokorny Transaction: 1929