FORCE AND MOTION
SUPPLIES: bucket of water, rocks, skateboard, ball
DISCUSSION: Sir Issac Newton – lived in 1600s (more than 400 years ago) in
England and was raised by his grandmother. He was a famous mathematician and
scientist and was the first scientist to explain how rainbows form and he was the
first to explain that gravity was the reason objects fall to the earth when you drop
them.
He came up with 3 “laws” of motion called “Newton’s Laws.” These were ideas
(hypothesis) about how motion works. And they’ve been tested and tested and still
found to be true.
INERTIA
Newton’s First Law – an object at rest tends to stay at rest, object in motion
tends to stay in motion, UNLESS acted upon by an outside force.
Ask kids what this means.
If I am standing here, what kinds of forces could put me in motion? (push, pull, by
another person, by the wind, by a dog)
What are examples of forces that might stop or move an object? (gravity, friction,
running into something, etc.)
If I throw a ball up in the air, what kind of force would stop it from flying into outer
space? (Gravity pulling it down)
Ask kids to think of other examples of Newton’s First Law:
 leaves that fall off trees will stay put until the wind blows them
 If you are riding a skateboard and the skateboard hits a rock and stops,
what happens to you (you keep going until you hit the ground)
ACCELERATION
Newton’s Second Law: Acceleration of an object depends on force and mass.
What does this mean?
 What is acceleration? (how fast something speeds up)
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What is mass? (how heavy something is)
What is force? (a push or pull)
Do you think an object will speed up faster with a lot of force or a little force?
What’s an example? [If you push down on the pedals of a bike lightly it will go
slower, than if you push down hard on the pedals.]
Do you think a heavy or lighter object will speed up faster? What’s an example?
[what if you throw a baseball and a heavy weight with the same force, which will
speed up faster?]
How many of you have been off a diving board? Do you go higher faster if you jump
hard or softly?
Can you think of some other examples of Newton’s Second Law?
EQUAL AND OPPOSITE REACTIONS
Newton’s Third Law: For every action, there is an equal (in magnitude) and
opposite (in direction) reaction.
What does this mean?
Have kids get in pairs and put their hands together and push off of each other. Their
push forward will also make them move backwards.
How is swimming the breast stroke an example of Newton’s Third Law – you use
your arms to push the water backwards and you get pushed forwards.
What happens if you fill a balloon with air and then let it go? How is that an example
of Newton’s Third law?
Can you think of other examples of Newton’s Third Law?
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ACTIVITY:
We’re going to break into three groups and go to different spots in the garden. Each
group will be assigned one of Newton’s laws. The group will talk about the law and
what it means, think of some examples, and the use object they have been given to
try to demonstrate the law. (Don’t give them the object until after talking about the
law)
Then the group will plan how to explain and use their object to demonstrate their
law to the rest of the class (making sure everyone gets to do part of the explanation.)
After 15-20 minutes, we’ll get back together and each group will explain their law to
the class.
[you might want to print out a description of each law to give to the relevant group]
FIRST LAW: AN OBJECT AT REST TENDS TO STAY AT REST; AN OBJECT IN
MOTION TENDS TO STAY IN MOTION
Give this group a call and tell them to figure out a way to use it to demonstrate and
explain Newton’s First Law to the Class. (eg. they might show that the ball stays
still until someone kicks/throws the ball. What forces stop the ball? Friction,
gravity, someone catching it or kicking it the other direction)
SECOND LAW: ACCELERATION OF AN OBJECT DEPENDS ON FORCE AND MASS.
Give this group a skateboard and tell them to figure out a way to use it to
demonstrate and explain Newton’s Second Law to the Class. TELL THE KIDS THEY
CANNOT STAND UP ON THE SKATEBOARD, BUT CAN PUSH IT, PULL IT OR SIT ON
IT. (eg. they might show that if they push the skateboard with nothing on it and it
speeds up fast, put something heavy on the skateboard and push it with the same
force and it will speed up more slowly)
THIRD LAW: FOR EVERY ACTION, THERE IS AN EQUAL (IN MAGNITUDE) AND
OPPOSITE (IN DIRECTION) REACTION.
Give this group a tub of water and rocks, and tell them to figure out a way to use
them to demonstrate and explain Newton’s Third Law to the Class. (eg., they might
show that if they throw the rocks down into the water, the water will splash back up
in the air)