Forces in Motion
Objective: Students can explain that for an object to move, accelerate/ decelerate, a force must be
applied and as the mass of the object increases more force is required. (Newton’s 1st Law)
Engage: Watch these videos with the class.
Ball Bouncing
Car rolling down
Trains moving passed each other
Slinky
1. What do these videos have in common?
2. Turn to the person next to you and share your answer to number 1.
3. What causes all of these things to move?
Explore:
Look at the photos below:
If I were to throw all these balls with the same amount of force, which one would go the furthest?
Why do you think that?
Explain:
Teacher leads a discussion as to how the objects will not move unless there is a force applied to
the object and the more massive an object, the more force is needed to get it to move, this is
called the law of inertia also known as Newton’s 1st law.
a. In order for an object to move, accelerate/decelerate, a force must act upon it
i. Introduce terminology of Newton’s 1st law: An object at rest stays at rest and an
object in motion stays in motion with the same speed and in the same direction
unless acted upon by an unbalanced force.
b. The more massive an object the more force is needed for it to get it to move, accelerate/
decelerate.
c. The larger mass ball traveled a smaller distance because it required more forced to get it
to move, the lighter mass objects traveled further because they required less force to get
it to move.
Elaborate:
Teacher leads a discussion as to whether the opposite is true as well; does it take more force to
stop an object with more mass?
a. “Do you think the opposite is true? Do you think that it takes more force to stop an
object if it has more mass?”
Evaluate:
Show students a video of car collision with a crash test dummy inside not wearing a seatbelt,
students describe why the crash test dummy continues to move even when the car has stopped
using Newton’s 1st law.
Using Newton’s 1st law, draw a model of what happens to a crash test dummy when the car is
in a collision.
Be sure to include the following:
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Before, During, After Picture
Labels
Terms that you have learned
Seen and the unseen
One sentence explanation