Review Questions

1. Questions 1–2 refer to the following diagram.

2. 

3. 1. A ball on the end of a string is swung in a horizontal circle, rotating clockwise as shown. When the ball is at point A, the direction of the velocity, centripetal force, and centripetal acceleration vectors, respectively, are

      1. 
      2. 
      3. 
      4. 
      5. 

   2. If the string were suddenly cut when the ball is at point A in the figure above, the subsequent motion of the ball would be

      1. to move to the right.
      2. to move to the left.
      3. to move to the top of the page.
      4. to move to the bottom of the page.
      5. to move up and to the left.

4. Questions 3–5 refer to the following diagram.

5. A 30 kg child sits on the edge of a carnival ride at a radius of 2 m. The ride makes 2 revolutions in 4 s.

   

6. 3. The period of revolution for this ride is

      1. 
      2. 
      3. 2 rev/s.
      4. 2 s.
      5. 4 s.

   4. The speed of the child is most nearly

      1. 4 m/s.
      2. 6 m/s.
      3. 24 m/s.
      4. 120 m/s.
      5. 360 m/s.

   5. The force that is holding the child on the ride is most nearly

      1. 30 N.
      2. 180 N.
      3. 300 N.
      4. 540 N.
      5. 4,320 N.

6. Torque

   1. is the vector product of force and lever arm length.
   2. is a scalar and has no direction associated with it.
   3. is always equal to force.
   4. is always greater for shorter lever arms.
   5. must always equal zero.

7. Two blocks of mass 3 kg and 4 kg hang from the ends of a rod of negligible mass marked in seven equal parts.

   

   At which of the points indicated should a string be attached if the rod is to remain horizontal when suspended from the string?

   1. A
   2. B
   3. C
   4. D
   5. E

8. A ball is tied to a string that passes through a glass tube and is attached to a hanging mass.

   

   The tube is held vertically as the ball is swung in a horizontal circle at a radius r and speed v. If the string is pulled through the tube by hanging a larger mass on the string so that the radius becomes the speed of the ball will become

   1. 
   2. 2 v.
   3. 3 v.
   4. 4 v.
   5. v (unchanged).