12. What are forces acting on the crate?
a. Normal force, weight and applied force F
b. Normal force, weight, applied force F and friction force
c. Normal force, weight, applied force F and Tension
d. Normal force, weight, applied force F, friction force and Tension
13. What is the acceleration of the crate?
a. 2.25 m/s², left
b. 2.25 m/s², right
c. 0.23 m/s², left
d. 0.23 m/s², right
14. Similar to other forces, friction is a force that affects motion. Friction occurs in
a. solids sliding over one another.
b. air.
c. liquids.
d. all of these.
15. The same net force is applied to object A and object B. It is observed that object A has an acceleration three times that of object B. Which of the following is correct?
a. Object A has three times the mass of object B.
b. Object A has one-third the mass of object B.
c. Object A has a different, less streamlined shape than object B.
d. Object A has more friction than object B.
16. What is the net external force on an object in free fall if you were to neglect the effect of air?
a. zero
b. upward with magnitude mg
c. downward with magnitude mg
d. downward with magnitude 9.8 N
17. If a net force acts on a horse while it is pulling a wagon, the horse
a. accelerates
b. is controlled
c. is pulled backward by an equal and opposite net force.
d. cannot move
18. A 65-kg swimmer pushes on the pool wall and accelerates at 6 m/s². The friction experienced by the swimmer is 100 N. What is the magnitude of the force that the swimmer applies on the wall?
19. Whenever one object exerts a force on a second object, the second object exerts a force on the first that is
a. opposite in direction and equal in magnitude at the same time.
b. in the same direction and equal in magnitude a moment later.
c. opposite in direction and greater in magnitude at the same time.
d. in the same direction and weaker in magnitude a moment later.
20. Two cars, one of mass 500kg and one of mass 250kg, collide head on. The car with more mass experiences a(n) _____ force and a(n) _____ acceleration with respect to the smaller car.
21. A locomotive is pushing a train at a constant velocity of 3 m/s. How does the force exerted by the locomotive on the train relate to the force of the train on the locomotive?
a. They are the same in both magnitude and direction
b. They are in opposite directions and have different magnitudes
c. They are in the same direction and have the same magnitude
d. They are the same in magnitude and opposite in direction
22. When you whirl a sling bag in a horizontal circle overhead, the force that holds the bag in the path acts
a. in an inward direction.
b. in an outward direction.
c. in either an inward or outward direction.
d. parallel to the force of gravity.
23. A car travels in a circle with constant speed. The net force on the car
a. is zero because the car is not accelerating.
b. is directed forward, in the direction of travel.
c. is directed toward the center of the curve.
d. none of the above
24. If you whirl a tin can on the end of a string and the string suddenly breaks, the can will
a. fly directly away from you.
b. fly off, tangent to its circular path.
c. fly directly toward you.
d. spiral away from your hand.