INV - Constant Acceleration
Lab Notebook Organization
On the next clean page of your lab notebook…
Title the page “INV Constant Acceleration”
Don’t forget to date the page!
In the Table of Contents…
List “ INV Constant Acceleration (and
the page it starts on)”
WDYT?
• An automobile and a bus are stopped
at a traffic light. What are some
differences and similarities of the
motion of these two
vehicles as each goes
from a stop to the speed
limit of 30 mi/hr?
Investigate - PURPOSES
• To define acceleration using strobe photos and
graphs of motion.
• To distinguish between positive and negative
acceleration using strobe photos and graphs of
motion.
**Complete investigation in your lab notebook.**
INV – Model 0 (Strobe Photos)
Learning Targets:
What is acceleration?
What do you know about
an object if it has:
– a positive acceleration?
– a negative acceleration?
Debrief - Model 0 (Strobe Photos)
Fruit Basket Upset
(Refining Your Thinking)
• Share home group’s thinking. Ask clarifying questions of
each other.
– #1-5
– How do you determine if acceleration is positive? Negative?
Share Out
(Whole class)
• #3-5
• What is “acceleration”?
• Positive vs. Negative acceleration?
How do you know?
Wednesday (9/23/15)
1. Self-Assessment
2. INV – Constant Acceleration
1. Debrief Model #0 (+/- acceleration)
2. Set up SNs for Model #1
3. Models #1-5 - Motion Sensors
Self- Assessment:
+ or – velocity?
+ or – acceleration?
1)
2)
3)
4)
Assume that the car is always in
“Drive” and not “Reverse”.
v
a
(+ or -)
(+ or -)
Debrief - Model 0 (Strobe Photos)
Share Out
(Whole class)
• #3-5
• What is “acceleration”?
• Positive vs. Negative acceleration?
How do you know?
Before Data Collection
1. Set up SN for Model #1
(show mine)
2. Ranking Task – Strobe Photos
INV – Constant Acceleration
Models #1-5: Carts on a Ramp
• Roles:
–
A=Recorder
B=Eq.Man./Reader
C=Facilitator
D=Spokesperson
• Safety:
Don’t let carts roll off counter (keep on track). Don’t let carts hit
motion detectors. Carpet against wall to stop carts.
• Model:
– 0 books for shallow incline; 1 book for steep incline
– POSITIVE DIRECTION: Post-it Note showing positive direction
– Sketch SETUP and PREDICTIONS of d-t, v-t, a-t graphs BEFORE testing
(SAMPLE of notebook entry… Next Slide)
Record slopes, means, etc.
Objectives:
– LabQuest Tips
•
•
•
•
next to graphs
Switching between v-t and a-t graphs
Slope at specific point – Use “Tangent”
Slope of linear section of graph – Use “Curve Fit > Linear”
Mean – Use “Statistics”
Strive to understand the data/graphs as you collect 
1. Compare & contrast
d-t, v-t, & a-t graphs
of accelerating
motion.
2. Distinguish b/w +
and – acceleration.
KaHoot – Motion Graphs (level 1)
Warm-Up (1/2 way through INV)
1.
What does positive acceleration mean? How do you identify it?
Sign of accel. is direction of force
2.
What does the slope of any point on a d-t graph tell you about the
motion of the object? Evidence?
(Groups demonstrate evidence they collected to determine this using the LabQuest under ELMO.)
3.
What does the slope of a v-t graph tell you about the motion of the
object? Evidence?
(Groups demonstrate evidence they collected to determine this using the LabQuest under ELMO.)
4.
Uphill is defined as the positive direction. A ball is released from
the top of the hill and it rolls down. What do you know about the
sign of the:
a)
b)
c)
Displacement?
Velocity?
Acceleration?
Check for Understanding
1. The slope of a d-t graph is velocity. The slope of a
v-t graph is
.
2. A car is traveling to the left (-). What type of motion
is the following strobe photo showing: positive or
negative acceleration? Explain your choice.
3. What is a similarity and a difference of d
the two d-t graphs to the right?
Sketch the v-t graphs for each.
4.
d
t
t
What is a similarity and a difference of
the two d-t graphs to the left? Sketch
the v-t graph of each.
SAVE FOR 1.4
Debrief 1.4 INV
(Show all graphs at once)
1)
Slope of d-t graph is _____________.
2-3)
Slope of v-t graph is _____________.
-Units for slope of v-t graph: _____
9-11)
Turn-around point on d-t, v-t, a-t graphs? Explain.
FA - Warm-Up
1. Describe the motion shown between
t=2s and t=5s in the d-t graph to the
right. Be sure your answer is as
descriptive as possible. Show your
work (as always ).
2. Sketch a d-t, v-t, and a-t graph for an
object slowing down as it moves in a
positive direction.
Graphing Constant Acceleration
1. Which graph(s) show(s)
positive acceleration?
What motion is occurring?
v (m/s)
A
B
C
D
t (s)
2. Which graph(s) show(s)
negative acceleration?
What motion is occurring?
3. Draw the d-t and a-t
graphs for each v-t graph.
1.4 Notes
Constant Velocity
Constant Acceleration
Definition and Details
about…
Algebraic Equations.
Give the equation and units
for each quantity..
Strobe Photos.
Draw and describe in
words what you would see.
Distance-time graph
Distance-time graph
Velocity-time graph
Velocity-time graph
Motion Graphs.
Draw and explain the
graphs produced by this
motion.
Acceleration-time graph
Constant Acceleration
Acceleration - The rate at which an object changes velocity..
Constant Acceleration – The change in velocity of an object each second is the same.
Definition and
Details about…
Algebraic Equations.
Give the equation and
units for each quantity..
Strobe Photos.
Draw and describe in
words what you would
see.
Distance-time graph
Velocity-time graph
Which colored graph
above do each of these
lines represent? Discuss
as a group.
Motion Graphs.
Draw and explain the
graphs produced by this
motion.
Acceleration-time graph
Example Problem: (page 68)
8. At an international auto race, a race car
leaves the pit after a refueling stop and
accelerates uniformly to a speed of
75 m/s in 9 s to rejoin the race. What is the
race car’s acceleration during this time?
(answer: 8.33 m/s2, 8 m/s2 with correct sig figs)
You Do
8.5) A driver is driving north (+ direction) at 60
mi/h when he sees a deer in the middle of the
road. What was his acceleration if he hits his
brakes and slows to a speed of 25 mi/h in 5
seconds.
[Ans: -7 mi/hr/s]
You Do
8.75) Use the following graph to answer the questions.
A. Describe the motion of the object shown.
B. Determine the acceleration of the object between
t=2s and t=6s.
Quick Warm-Up
Sketch a d-t, v-t, and a-t graph for an object slowing down
as it moves in a negative direction.
Requirements to Test
Wkst – “Practice w/ Motion Graphs”
#1-6:
• 1st - Describe motion in words (direction and what is happening to velocity)
• 2nd - Describe motion with numbers (Show work)
• 3rd - Draw v-t graph that corresponds with top graph
#7-11:
• Answer questions
• Draw a-t graph that corresponds
with bottom graph
9/18/15 Part 1Checklist & Spiral Review
1. Checklist –
a)
b)
STAPLE (have SN open to 1.4 INV.)
SELF CHECK:
a)
b)
c)
PEER CHECK:
a)
d)
Check off which of the 5 required assignments are completed
Sign your name
Check that the marked assignments are completed (don’t forget to
check 1.4 INV in the Science Notebook) and sign it.
TEACHER CHECK: Checking 1.4 INV
e) TURN IN to red tray
2. Spiral Review ---- do this while you wait
(HW for tomorrow)
Chalk Graphs – Practice Motion  Graphs
• Purpose: Draw motion graphs to represent motion.
• Groups: 2 per group (Your choice – choose wisely )
• Bring out:
– Page in sheet protector
– Chalk
• Checking your graphs:
– I will be rotating around to check & answer questions.
– Motion sensor & LabQuest - Test it out
– Peer Experts could check
Distance-Time Graphs
The object is…
1.
Moving away from the
position s=0 at a
constant velocity. (A)
2.
Moving toward the
position s=0 at a
constant velocity. (B
and C)
3.
Velocity is increasing at
a uniform rate. (1st half
of G and H, ¼ and ¾ of I)
4.
Velocity is decreasing at
a uniform rate. (last half
of G and H, 2/4 and 4/4
of I)
5.
Changes direction (H
and I)
6.
Standing still for an
extended period of time
(D, E, F)
7.
Momentarily at rest on
one occasion. (none)
8.
Momentarily at rest on
two separate occasions.
(G and H)
Velocity-Time Graphs
The object is…
1. Moving away from
the position s = 0 at
a constant velocity.
(F)
2. Moving toward the
position s=0 at a
constant velocity. (E)
3. Velocity is increasing
at a uniform rate. (A)
4. Velocity is decreasing
at a uniform rate. (B
and C)
5. Changes direction
(G)
6. Standing still for an
extended period of
time (D)
7. Momentarily at rest
on one occasion. (A,
B, C, G and I)
8. Momentarily at rest
on two separate
occasions. (H)
Example Problem: (page 68)
9.
During a softball game, a player running from second base
to third base reaches a speed of 4.5 m/s before she starts to
slide into third base. When she reaches third base 1.3 s after
beginning her slide, her speed is reduced to 0.6 m/s. What is
the player’s acceleration during the slide? If she slid for only
1.1 s, how fast would she have been moving when she
reached third base?
(answer: -3 m/s2, 1.2 m/s)
WDYTN?
An automobile and a bus are stopped at a traffic
light. Draw the d-t, v-t and a-t graphs for both
vehicles as each goes from a stop to the speed limit
of 30 mi/h?
***It will be easier to compare motions if you
place both graphs on the same set of axes for
each type of graph.***
d (m)
t (s)
http://www.arborsci.com/next-time-questions
Whiteboard Practice
FA #2 - Warm-Up
1. A bungee jumper leaps off the side of a bridge causing
the jumper to plummet towards the ground. Draw the dt, v-t, and a-t graphs showing the jumper’s motion:
– from the time the bungee cord begins pulling up on the jumper as
he is falling,
– to the time he gets to the lowest point of his motion,
– to the time when he is back up to where the rope has some slack
again.
Assume that up is the + direction.
Random Error
• Inherent to the measuring device -OR- how the
device is used (tool or person)
– Causes uncertainty (+/- 0.1)
• It leads to variation in the data.
• It cannot be corrected for by
a calculation.
Systematic Error
• A repeated error.
• Causes a shift in data away
from the accepted value.
• It can be corrected for with a
calculation.
• Examples?
Accuracy vs. Precision (p. 26-27)
• Accuracy is …
being close to the actual value.
– So accuracy has low
• Precision is…
systematic
error.
being consistent.
– Precision has low
random
error.
Practice: #1
Four groups of students measure a football field using four different measurement
tools. The accepted length of a football field (including the end zones) is 120 yards.
Match each of the four groups to the four descriptions (A-D) below:
Length of a football field
Trial
Group 1
(yards)
Group 2
(yards)
Group 3
(yards)
Group 4
(yards)
1
120.1
84.0
99.9
110.0
2
120.0
117.0
100.3
125.0
3
119.8
105.0
100.1
127.0
4
119.9
93.0
100.1
117.0
Average
120.
100.5
100.1
119.8
A
B
C
D
Which group(s) had low random error?
Accurate and Precise
Accurate but Imprecise
Inaccurate but Precise
Inaccurate and Imprecise
Which group(s) had high systematic error?
Review Day for Test
1.
2.
Warm-Up (do it on desk)
Return Work & Checklist
3.
Review Error Types
4.
Check Spiral Review – Learn from errors
5.
Options:
1.
2.
3.
Draw d-t, v-t, a-t graphs to match 4 strobe photos on front of 1.4 INV
Do 1.4 INV again and make predictions and then test
Stations:
Challenge Problem
1. Describe the motion shown in the diagram below.
2. Draw the v-t and a-t graphs that represent this motion.
3. Using a motion sensor and LabQuest, produce this
graph and check your v-t and a-t graphs. (Pushing a cart to
make this motion may be easier than walking.)