F=ma

Two objects, A and B, move toward one another. Object A has twice the mass and half the speed of object B. Which of the following describes the forces the objects exert on each other when they collide and provides the best explanation?

• The force exerted by A on B will be twice as great as the force exerted by B on A, because A has twice the mass of B.

• The forces exerted by each object on the other are the same, because interacting objects cannot exert forces of different magnitude on each other.

• The force exerted by A on B will be half as great as the force exerted by B on A, because A has half the speed of B.

• The forces exerted by A on B will be twice as great as the force exerted by B on A, because A has half the speed of B.

For which of the following objects will be the net force acting on it be zero?

• A football is thrown straight up into the air

• A hamburger in free-fall.

• A crate being pushed uphill at constant speed.

• A mine cart traveling uphill and slowing down until it rolls back down the hill.

A teacher drags a suitcase across the ground at Miami International Airport after running away from teaching virtually. The frictional force of the floor on a large suitcase is least when the suitcase is:

• dragged by a force parallel to the floor

• pulled by a force directed at an angle above the floor.

• pushed by a force directed at an angle into the floor

• turned on its side and pushed by a force parallel to the floor.

The more massive an object is...

• the harder it will be to get moving.

• The harder it will be to stop.

• the harder it will be to speed up.

• all of the above.

An object's tendency to resist (not) change its state of motion is

• gravity

• friction

• inertia

• momentum

What is the net force?

• 65 N left

• 65 N right

• 35 N left

• 35 N right

What is the net force?

• 11 N left

• 11 N right

• 3 N left

• 3 N right

The diagram below shows a skateboarder pushing himself forward with a force of 25 N while the wind pushes back with a force of 5 N. How will the skateboarder be affected if the force of the wind increases to 8 N?

• The speed of the skateboarder will increase.

• The speed of the skateboarder will remain constant.

• The speed of the skateboarder will decrease.

• The skateboarder will come to a stop.

A group of students places weights onto 4 different carts. The students pull each of the carts with the same amount of force. Which cart has the least change in speed?

• A

• B

• C

• D