physgrl

1. The problem statement, all variables and given/known data

9. A force can change angular rotational if it acts through:

a. the axis of rotation

*b. a lever arm tangential to the direction of rotation

c. a moment arm parallel to the axis of rotation

d. none of these

2. Relevant equations

n/a

3. The attempt at a solution

I would like to understand why b is the correct answer.