Physics 221 Worksheet: Chapter 8, Rotation

1) Which of the following is not suitable for expressing angular velocity?

a) rad/s

b) R.P.M.

c) rev/s

d) m/s

2) The rate of change of angular velocity is measured in:

a) rad

b) rad/s

c) rad/s²

d) rad²/s²

3) A bicycle with 70 cm diameter wheels is moving at 10 m/s. Each wheel’s angular velocity is:

a) 700 rad /s

b) 0.035 rad/s

c) 3.5 rad/s

d) 28.6 rad/s

4) To calculate the angular acceleration of an object:

a) divide the applied torque by its moment of inertia.

b) divide its moment of inertia by the applied torque.

c) multiply its moment of inertia by the applied torque.

5) An object’s moment of inertia will change if you change its:

a) mass.

b) size.

c) shape.

d) all of the above.

e) none of the above.

6) A ball, a hoop, and a cylinder each have the same mass and radius.

a) The ball has the largest moment of inertia.

b) The hoop has the largest moment of inertia.

c) The cylinder has the largest moment of inertia.

d) All three have the same moment of inertia.

7) A rotating ball, hoop, and cylinder each have the same mass, radius and kinetic energy.

a) The ball has the highest angular velocity.

b) The hoop has the highest angular velocity.

c) The cylinder has the highest angular velocity.

d) All have the same angular velocity.

8) When a spinning skater extends her arms she slows down. This is explained by the law of:

a) conservation of energy.

b) conservation of momentum.

c) conservation of angular momentum.

d) conservation of angular velocity.

9) A force’s effectiveness in producing rotation is called:

a) torque.

b) energy.

c) angular momentum.

Ans: 1-d, 2-c, 3-d, 4-a, 5-d, 6-b, 7-a, 8-c, 9-a

Physics 221 Worksheet: Chapter 8, Torque

1) Calculate the torque of the given force about the axis shown.

a) b)

d)

c)

2) Calculate the resultant torque about the axis. Indicate clockwise or counterclockwise.

a) b)

Ans:

#1 a) +4.32 Nm b) +3.31 Mn c) –22.0 Nm d) +46.0 Nm #2 a) +0.96 Nm b) –0.407 Nm