Which statement BEST describes angular acceleration?

Which statement BEST describes angular acceleration?

• A. Change in speed only
• B. Change in direction only
• C. Change in both speed and direction
• D. No change in motion

Answer: (C)

Angular acceleration is the rate at which the angular velocity changes. Angular velocity is a vector with both magnitude (how fast it spins) and direction (the axis of rotation). If the spin slows down or speeds up, the magnitude changes; if the axis tilts or the rotation plane changes, the direction changes. Any time the angular velocity vector changes in time, you have angular acceleration. Therefore, the statement that best describes it is that there is a change in both speed and direction, because angular velocity can change in either aspect or in combination. A change in speed only describes a magnitude change, and a change in direction only describes a direction change; angular acceleration can occur with either, and no change at all is not correct.

Angular acceleration is the rate at which the angular velocity changes. Angular velocity is a vector with both magnitude (how fast it spins) and direction (the axis of rotation). If the spin slows down or speeds up, the magnitude changes; if the axis tilts or the rotation plane changes, the direction changes. Any time the angular velocity vector changes in time, you have angular acceleration. Therefore, the statement that best describes it is that there is a change in both speed and direction, because angular velocity can change in either aspect or in combination. A change in speed only describes a magnitude change, and a change in direction only describes a direction change; angular acceleration can occur with either, and no change at all is not correct.