Force and Motion

Front

Why does the ball bounce backward when it hits the target?

Back

The target exerts the same size force on the ball, so when the target moves in one direction, the ball moves in the opposite direction.

Front

A box has two forces acting on it. One force is 100 N upward. Another force is 50 N downward. What is the net force on the box?

Back

50 N upward

Front

Why is friction force considered to be a contact force?

Back

Friction acts in a direction opposite to the direction of an object’s motion.

Front

What force caused the baseball to accelerate downward when thrown?

Back

gravitational force

Front

A bird flies at 12.5 meters/second. The wind speed is 4.5 m/s. What is the speed of the bird when it flies with the wind?

Back

17 m/s

Front

A bird flies at 12.5 meters per second. The wind speed is 4.5 meters per second. What is the speed of the bird when it against the wind?

Back

8 m/s

Front

In which situation is it better to have low friction? Options: a student walks down a hallway, a hockey puck slides toward the goal, a ladder leans against the wall, a skydiver uses a parachute.

Back

a hockey puck slides toward the goal

Front

Why don't two basketballs sitting 1 m apart move due to gravitational force?

Back

The gravitational force between the two objects is weak because their masses are small.

Front

This diagram shows forces acting on a box. Predict how the box will move (in which direction and with what amount of net force)

Back

the box will move right with 50 N force

Front

An airplane is traveling at a speed of 200 m/s relative to the Earth. A person walks toward the front of the plane at a speed of 1 m/s. How fast is that person traveling in reference to the other people on the airplane?

Back

1 m/s