AP Physics I MC Laws of Motion

13. (MC) Starting a vehicle moving from rest on a horizontal surface on the moon requires (A) the same forward force. (B) less forward force, since mass on the moon is smaller. (C) less forward force, since weight on the moon is smaller. (D) more forward force, due to the absence of an atmosphere.

A

7. (MC) If mass doubles while a constant force is applied, then acceleration is changed by a factor of (A) 1/2 (B) 1 (C) 2 (D)4

A

1. (MC) Which is true for mass? (Select two answers) (A) It is the amount of matter an object consists of. (B) It is an objects weight. (C) Inertia is a consequence of having mass. (D) It changes with the strength of gravity g.

A, C

41. (MC) The friction force acting on a mass is influenced by (Select two answers) (A) the roughness of the surfaces (B) the area of the surfaces that contact each other (C) the force of the surfaces pressing together (D) the speed of the object

A, C

Newton's First Law

An object at rest or an object in a constant state of motion will stay at rest or continue its motion unless acted upon by an unbalanced force

22. (MC) Two objects with different masses are dropped from the same height with no air resistance. They reach the ground at the same time because (A) mass is not a factor and has no effect on acceleration. (B) the more massive object has more inertia and requires more force to accelerate at the same rate. (C) the same net force acts on both objects, creating the same acceleration. (D) weight is not a factor in acceleration of dropped objects.

B

35. (MC) Two different objects have the same density and both weigh 100 N. However, one is on a planet where gravity is greater than on earth. Which object is larger? (A) Mass of an object does not change on new planets. (B) The object on Earth is larger. (C) The object on the other planet is larger. (D) The scales read incorrectly due to the gravity change, and both objects are the same size.

B

2. (MC) Which is true for weight? (Select two answers) (A) It is the same everywhere regardless of gravity. (B) It is a vector, while mass is a scalar. (C) It is the force acting on mass in a gravity field. (D) It is the same as mass. The force of gravity is g.

B, C

53. (MC) An object is in free fall in the presence of air resistance. Prior to reaching terminal velocity its (Select two answers) (A) velocity decreases (B) velocity increases (C) acceleration decreases (D) acceleration increases

B, C

17. (MC) Which is true for a rocket moving upward? (A) Exhaust gases push on the Earth creating an equal and opposite upward force. (B) Exhaust gases push on air molecules creating an equal and opposite upward force. (C) Exhaust gases pushed backwards by the rocket are the action force, and the rocket moving in the opposite direction is the reaction force. (D) The force of the exhaust gases is small and doesn't add too much downward force to gravity. If they do the rocket will not have enough upward force.

C

19. (MC) An object at rest has a 5 N +x force applied to it. After moving for 10 s a second 5 N −x force also acts on the object. Describe the objects motion. (A) Accelerates for 10 s, and then decelerates. (B) Constant velocity for 10 s, and then stops. (C) Accelerates for 10 s, and then constant velocity. (D) Constant velocity for 10 s, and then decelerates.

C

20. (MC) When an object is thrown upward, in the absence of air resistance, and reaches the top of its trajectory it stops instantaneously. At this point the net force on the object is (A) g (B) zero (C) mg (D) changing

C

3. (MC) The tendency to maintain velocity is caused by (A) force and stated in Newton's 1st Law. (B) force and stated in Newton's 2nd Law. (C) inertia and stated in Newton's 2nd Law. (D) mass and stated in Newton's 1st Law.

C

6. (MC) If the force acting on an object doubles, its acceleration is changed by a factor of (A) 1/2 (B) 1 (C) 2 (D)4

C

10. (MC) If the mass of an object is suddenly quadrupled, then the object's acceleration is changed by a factor of (A) 1/4 (B) 1 (C) 4 (D) answer also depends on changes to acting forces

D

16. (MC) When you push on an object the reaction force depends on (A) the object's mass (B) your mass (C) the objects speed (D) the action force

D

29. (MC) An object hangs in static equilibrium from two ropes. Which answer is true in every possible case? (A) Each rope supports the objects weight. (B) The tension in the two ropes adds to the objects total weight. (C) The vertical components of each ropes tension support half the objects weight. (D) The vertical components of tension add together to equal the objects weight.

D

54. (MC) When a skydiver reaches terminal velocity, the magnitude of velocity is (A) zero (B) decreasing (C) increasing (D) constant

D

Newton's Second Law

The acceleration of an object is directly proportional to the unbalanced force applied to the object, and it is inversely proportional to the object's mass

Newton's Third Law

Whenever two objects interact there is an equal and opposite force between them