Newton's Second Law - AP Physics 1: Unit 2 Review Supplement

A rock is freely falling downward toward the Earth. The weight of the rock is W. Which of the following best describes the force from the rock on the Earth as the rock falls?

• Zero

• W upward

• W downward

• Increasing in magnitude as the rock's speed increases.

A book rests on a table. According to Newton's Third Law, the reaction force to the force of the table pushing up on the book is:

• The force of the Earth pulling down on the book.

• The force of the book pushing down on the table.

• The force of the table pushing down on the Earth.

• The force of the book pulling up on the Earth.

An object with a mass of 30 kg is accelerating North at 1 m/s². If a 40 N force acts East and a second force F2 is also acting, what is the magnitude of the y-component of F2?

• 10 N

• 30 N

• 40 N

• 50 N

A 30 kg object accelerates North at 1 m/s². A force, F1, of 40 N acts due East on the object. If there is only one other force, F2, acting on the object, what is the magnitude and direction of F2?

• 50 N @ 37° North of West

• 50 N @ 53° North of West

• 35 N @ 37° North of West

• 35 N @ 53° North of West

For an object to have constant velocity in the y-direction and constant acceleration in the x-direction (both non-zero), what must be true about the net forces?

• The net force in the y-direction must be zero, and the net force in the x-direction must be non-zero.

• The net force in the y-direction must be non-zero, and the net force in the x-direction must be zero.

• Both the net force in the y-direction and the net force in the x-direction must be zero.

• Both the net force in the y-direction and the net force in the x-direction must be non-zero.

Consider a free-body diagram with three force vectors: one 2 units up, one 4 units left, and one 4 units right and 2 units down. What are the net forces in the x and y directions for this diagram? (Assume positive x is right and positive y is up. Each grid square represents one unit of force.)

• Net Fx = 0, Net Fy = 0

• Net Fx = 4 units right, Net Fy = 0

• Net Fx = 0, Net Fy = 2 units up

• Net Fx = 4 units left, Net Fy = 2 units down