### Concept Items

#### 6.1 Angle of Rotation and Angular Velocity

- 1\,\text{rev} = \pi\,\text{rad}=180^\circ
- 1\,\text{rev} = \pi\,\text{rad}=360^\circ\!
- 1\,\text{rev} = 2\pi\,\text{rad} = 180^\circ\!
- 1\,\text{rev} = 2\pi\,\text{rad}=360^\circ

- Tangential velocity is the average linear velocity of an object in a circular motion.
- Tangential velocity is the instantaneous linear velocity of an object undergoing rotational motion.
- Tangential velocity is the average angular velocity of an object in a circular motion.
- Tangential velocity is the instantaneous angular velocity of an object in a circular motion.

What kind of motion is called *spin*?

- Spin is rotational motion of an object about an axis parallel to the axis of the object.
- Spin is translational motion of an object about an axis parallel to the axis of the object.
- Spin is the rotational motion of an object about its center of mass.
- Spin is translational motion of an object about its own axis.

#### 6.2 Uniform Circular Motion

- a_c = \frac{\omega^2\!}{r}
- a_c = \frac{\omega}{r}
- a_c = r\omega^2\!
- a_c = r\omega\!

- F_c = \frac{a_c^2\!}{m}
- F_c = \frac{a_c}{m}
- F_c = ma_c^2\!
- F_c = ma_c

- center-seeking
- center-avoiding
- central force
- central acceleration

#### 6.3 Rotational Motion

Conventionally, for which direction of rotation of an object is angular acceleration considered positive?

- the positive
*x*direction of the coordinate system - the negative
*x*direction of the coordinate system - the counterclockwise direction
- the clockwise direction

- It opens slowly because the lever arm is shorter so the torque is large.
- It opens slowly because the lever arm is longer so the torque is large.
- It opens slowly because the lever arm is shorter so the torque is less.
- It opens slowly because the lever arm is longer so the torque is less.

- Angular acceleration is the rate of change of the displacement and is negative when \omega increases.
- Angular acceleration is the rate of change of the displacement and is negative when \omega decreases.
- Angular acceleration is the rate of change of angular velocity and is negative when \omega increases.
- Angular acceleration is the rate of change of angular velocity and is negative when \omega decreases.