Awheel is rotating about an axis that is in the

z-direction. the angular velocity ωz is -6.00 rad/s at t = 0, increases linearly with time, and is +4.00 rad/s at t = 16.0 s . we have taken counterclockwise rotation to be positive.

part a

is the angular acceleration during this time interval positive or negative?

part b

how long is the time interval during which the speed of the wheel is increasing?

express your answer with the appropriate units.

part c

how long is the time interval during which the speed of the wheel is decreasing?

express your answer with the appropriate units.

part d

what is the angular displacement of the wheel from t = 0 s to t = 16.0 s