A student gives a quick push to a ball at the end of a massless, rigid rod, as shown in FIGURE Q12.9, causing the ball to rotate clockwise in a horizontal circle. The rod€™s pivot is frictionless.
a. As the student is pushing, is the torque about the pivot positive, negative, or zero?
b. After the push has ended, does the ball€™s angular velocity 

(i) Steadily increase;

(ii) Increase for awhile, then hold steady;

(iii) Hold steady;

(iv) Decrease for awhile, then hold steady;

(v) Steadily decrease? Explain.
c. Right after the push has ended, is the torque positive, negative, or zero?

Pivot Push Top view FIGURE Q12.9