Force and Motion

Alfonso, Julia, and Margie were having fun as they rolled some office chairs across a flat floor. All three chairs have the same mass. Margie gave each of the chairs a push, but not all from the same direction. Each chair changed speed as a result of being pushed. Use the information in the diagram to answer. Which chair(s) experienced the strongest force when it was pushed? How do you know?

• The black chair experienced the strongest force because it takes a stronger force to slow something down than it takes to speed something up.

• The blue chair experienced the strongest force because it had the fastest ending speed.

• All three chairs experienced the same strength force because they changed speed by the same amount.

• The pink and blue chairs experienced the strongest forces because they both gained the same force as they sped up. The black chair lost force, so it slowed down.

Three boats were moving across the surface of a smooth lake. The gray and pink boats have the same mass, and both of these boats are more massive than the orange boat. Each boat was bumped by another boat, but not from the same direction. Use the information in the diagram to answer.

Which boat(s) experienced the strongest force when hit? How do you know?

• The gray and pink boats experienced the strongest force because they are both more massive than the orange boat, and they all changed speed by the same amount.

• The pink boat experienced the strongest force because it is as massive as the gray boat and has the highest ending speed.

• All three boats experienced the same force because they changed speed by the same amount.

• The gray boat experienced the strongest force because it takes more force to slow an object than it takes to make it go faster.

What is required to change the velocity of an object?

• Velocity

• Force

• mass

• infer

Which direction would you apply force in order to get an object to slow down or stop?

• any direction

• same direction as motion

• opposite direction of motion

• applying force cannot make an object stop or slow down

Which direction would you apply force in order to get an object to speed up?

• any direction

• same direction as motion

• opposite direction of motion

• applying force will not cause an object to speed up

Which of the following will cause a greater change in velocity?

• adding more mass

• adding more friction

• applying more force

• stopping an object