Which of the following is not used to reduce friction?

1. Which of the following is not used to reduce friction? • wheels • ball bearings • oil • rough surfaces

2. Which of the following is not a fluid? • air • Sugar • Water • oil

3. When forces are balanced, the motion of the object • is decreased. • is increased. • does not change. • is completely stopped.

4. For every action, the reaction is • equal and in the same direction. • equal and opposite. • unequal and opposite. • unequal and in the same direction.

5. Near the surface of the Earth, the acceleration due to gravity is 9.8 m/sec/sec. After falling 6 sec, an object would have a velocity of • 3.8 m/sec. • 9.8 m/sec • 15.8 m/sec. • 58.8 m/sec.

6. Acceleration is produced when a force acts on a mass is described by Newton’s • first law of motion. • second law of motion. • third law of motion. • law of universal gravitation.

7. The weight of an object varies with the • pull of gravity. • volume of the object. • dimensions of the object. • speed of the object.

8. Forces can cause objects to • stop moving only. • change direction only. • start moving only. • start moving, change direction, or stop moving.

9. A force that sets an object into motion is • balanced. • friction. • unbalanced. • inertia.

10. Wheels and ball bearings change sliding friction to • static friction. • rolling friction. • fluid friction • all types of friction.

11. The function of lubricants is to change • fluid friction to sliding friction. • fluid friction to rolling friction. • sliding friction to fluid friction. • sliding friction to rolling friction.

12. Treads on tires • increase friction. • reduce friction. • decrease stopping motion. • prevent the braking of a car.

13. An example of rolling friction is • a stack of cartons being pushed across a floor. • the use of ball bearings. • the fall of a feather through the air. • sand placed on an icy walk.

14. An example of friction other than sliding or rolling is • pushing a desk across a floor. • walking across a floor. • floating downward after diving off a cliff. • riding on a skateboard.

15. The sum of balanced forces equals • zero. • one. • two. • three.

16. The head of the arrow representing a force indicates the A. size of the force. • strength of the force. • direction of the force. • sum of the forces.

17. A standoff in an arm-wrestling match is due to • sliding frictional forces. • rolling frictional forces • fluid frictional forces. • balanced forces.

18. The combination of two forces exerted in opposite directions is the • sum of the two forces. • difference between the two forces. • product of the two forces. • ratio of the two forces.

19. If there is an unbalanced force in an arm-wrestling match, • both arms will move in the direction of the smaller force. • both arms will move in the direction of the larger force. • the arms will move in opposite directions. • the arms will be stationary.

20. The first law of motion states • that an object at rest will remain at rest. • that an object in motion will remain in motion at a constant velocity. • that an unbalanced force can change the velocity of an object in motion. • all of the above.

21. The law of motion that describes action-reaction is the • first law. • second law. • third law. • law of gravity.

22. Gravitational force between two objects depends on the • masses of the objects and the distance between them. • mass of each object only. • distance between the objects only. • inertia and masses of the objects.

23. A mass of 5 kg has a weight of • 5 kg m/sec/sec. • 5 N. • 49 kg m/sec. • 49 N.

24. If you were on the moon, there would be a change in your • weight and mass. • weight. • mass. • volume.

25. A force • is a push or a pull. • gives energy to an object. • can cause an object to change its motion. • can do all of the above.