Definitions:
Mass:
The amount of matter in an object.
Weight:
The measure of the pull of gravity between an
object and the Earth.
A force that acts pulls objects together. Depends on
how much mass is in an object. ( stronger pull if
more mass. Weaker pull if less mass) AND how far
apart objects are( Closer= strong pull/
farther=weaker pull)
Anything that pushes back against motion. Air
resistance and water resistance are examples.
Means opposite in direction
Gravity:
Resistance:
Opposing
Balanced
Force
Forces that cancel each other out. Force is equal in
size and opposite in direction. You sit on a chair.
Gravity pulls you down, the force of the chair pushes
you up.
Unbalanced
Force
Forces that are not equal and cause a change of
motion. You move in the direction of the
greater force. Ex. Dogs playing tug of war p 494
** Up thrust was omitted
1 ) How could you make a sheet of paper fall as quickly as possible?
A Cut the paper
B Crumple it into a ball
Why? By crumpling the paper up, it reduces the surface area. Less air pushes up stopping it from
falling. It falls quicker. Less surface area= less air resistance.
2) When an object falls, air resistance does what?
A
Pushes up as the object falls
B
Pushes the object down faster
Explain: Gravity is pulling the object down toward the center of the Earth. Air is in the way and pushes
up on the object slowing it down.
3) Weight is a force and is measured what?
A
grams
B inches
C Newons
4) Where would you feel the heaviest on the moon or on Earth and Why?
You would feel heaviest on the Earth because the Earth is larger and has more gravity. There is a
stronger pull on the Earth than on the moon. Mrs. Darmanin would rather use a scale on the moon
than on Earth!
5) Which of the following is true and why?
A
Gravity only acts through air, not water or land.
B
Gravity doesn’t act on airplanes flying in the sky.
C
Gravity always acts toward the center of the Earth through air, land, and water.
6) If gravity pulls you towards the center of the Earth, why don’t you fall through the pavement?
The pavement provides an upthrust or upward force holding you up on the surface.
7) What has more force?
A
An apple falling in water
B An apple falling in air
Why: Water is denser than air and has more upthrust or upward push. The apple will fall slower in the
water than in the air.
8 What is not a force?
A
Friction
B
Weight
C Height
Read each statement. Write “true” if the statement is true and “false” if the statement is false.
A moving object continues to move until a force stops it. ____True___________
A moving object eventually runs out of force and slows down. ____False, Remember Inertia, an object
doesn’t “run-out” of force, it will keep moving until a force acts on it. ______________________
A moving object travels in a line until a force changes its direction. ____True__________
10) When an object is at rest or stationary what kind of forces are acting on it?
A
Balanced Forces
B Unbalanced Forces
Why? Even though the object is not moving, there are still forces acting on it, but they are balanced.
The forces cancel each other out and the object doesn’t move. There is a force “equal” in size or
strength pushing the object down and one the same size “equal” in size or strength pushing it up. (Or
think of a tug of war. The rope doesn’t move if both sizes have “equal” forces. The forces are balanced
11) What is a good way to slow down on a bicycle?
A Drag your feet along the ground
B
Pedal faster.
C
Ask someone to give you a push.
Explain your answer: When you drag your feet the two objects touch creating friction which will stop
motion.
12) What is a good way to speed up on a slide?
A Hold onto the sides of the slide
B Wear slippery clothes
Explain your answer: The smoother your clothes the quicker you will slide because there will be less
friction.
13) Pushes and pulls of examples of
A
Forces
B Stretches
C Twists
14) When you push a toy car, it eventually stops. What causes it to stop?
A
Friction
B Gravity
C Twisting
Explain your answer: Both friction and gravity. Gravity is always acting on an object pulling it down
onto the surface. When the wheels rub along the ground, eventually friction occurs and stops the car.
15) With the same push, would a heavy car travel further or less far than a light car?
A
Further
B
Less Far
C
They’d both travel the same distance
Explain your answer: The more mass, the stronger the push needs to be in order to move the car. If
you use the same strength push, the car won’t go as far.
16) On what type of track would a sled move the fastest?
A
A flat track
B A gently sloping track
C A steeply sloping track
Explain your answer: When the car is lifted up it increases the gravitational pull. The sled will come
down the track the fastest. Think of what happened when we raised the gradient of the truck.
17) What else might affect the speed of the sled moving down the track?
A The color of the track
B The surface of the track
C The name of the track
Explain your answer: Think of the surface of the track. The smoother the track (ice or vinyl) the car
moved quicker. When the car was on carpet it moved slower. Friction between the surface affects the
speed of the sled.
Name _______________________________ Date ________________________________
BBC Forces in Action Video Clip
http://www.bbc.co.uk/schools/scienceclips/ages/10_11/forces_action.shtml
Factors that have an effect on motion:
___________________________________, ______________________________________,
___________________________________, ______________________________________,
Your Guess: We are going to release the truck. Guess where it will stop.
Your Guess
Truck alone
Gradient 1
Truck alone
Gradient 2
Truck with
Small
Parachute
Truck with
Small
Parachute
Truck with
Large
Parachute
Truck with
Large
Parachute
Truck with
Small Weight
Gradient 1
Truck with
Small Weight
Gradient 2
Truck with
Large Weight
Gradient 1
Truck with
Large Weight
Gradient 2
Gradient 2
Gradient 1
Gradient 2
Gradient 1
Actual
What did I learn: