A.4 Rigid body motion concepts review

1. The ​ (a)   of a body is a measure of the body’s ability to resist changes in its rotational motion.

2. A body is said to be in uniform circular motion when its ​ ​ (b)   is constant (and non-zero).

3. A body is said to be in uniform angularly accelerated motion when its ​ (c)   is constant (and non-zero).

4. If a body rolls along a surface, its kinetic energy is equal to the sum of its ​ (d)   and rotational kinetic energies.

• moment of inertia
• couple
• angular momentum
• force
• angular velocity
• angular acceleration
• translational

5. ​ ​ (a)   quantifies the turning effect of a force.

6. Rotation often results from the action of a pair of equal and opposite forces, known as a ​ (b)   .

7. A body is in translational equilibrium if the ​ (c)   on it is zero.

8. A body is in ​ (d)   if the resultant torque on it is zero.

• torque
• translational equilibrium
• resultant torque
• resultant force
• rotational equilibrium
• couple

9. A body’s angular acceleration is directly proportional to the ​ (a)   on the body.

10. ​ The (b)   is conserved if the resultant external torque is zero.

11. The ​ (c)   on a body is equal to the body’s change in momentum, resulting from the action of a resultant torque.

• resultant torque
• resultant force
• angular momentum
• angular impulse
• angular acceleration
• moment of inertia

Match the following

• Rotational kinetic energy

• 
• Resultant torque

• 
• Angular momentum

• 

Match the following

• Torque

• 
• Angular impulse

• 
• Work done

• 
• Rotational kinetic energy

• 

The solid dot shown in the figure is a pivot point. The board

can rotate about the pivot. Which force shown exerts the largest magnitude torque on the board?

• a

• b

• c

• d

• e

Consider a force F = 80 N applied to a beam as shown in figure, the length of the beam is l = 5.0 m, and theta = 37°, so that x = 3 m and y = 4 m, of the followings, which ones give the correct torque produced by the force around point P?

• (48 N)(5.0 m)

• (48 N)(4.0 m)(sin 37°)

• (80 N)(5.0 m)(sin 37°)

• (80 N)(4.0 m)

• (80 N)(3.0 m)

A small mass m on a string is rotating without friction in a circle. The string is shortened by pulling it through the axis of rotation without any external torque, What happens to the angular velocity of the object?

• It increases.

• It decreases.

• It remains the same.

A small mass m on a string is rotating without friction in a circle. The string is shortened by pulling it through the axis of rotation without any external torque, What happens to the linear velocity of the object?

• It increases.

• It decreases.

• It remains the same.

Suppose you are sitting on a rotating stool holding a 2-kg mass in each outstretched hand. If you suddenly drop the masses, your angular velocity will

• increase.

• decrease.

• stay the same.