A particle starts from rest and moves along a circular path with constant angular acceleration. During the time interval
from $\mathrm{t}=4 \mathrm{~s}$ to $\mathrm{t}=4.8 \mathrm{~s}$, its average angular velocity was $44 \mathrm{rad} \mathrm{s}^{-1}$.
(a) Its angular velocity at $4 \mathrm{~s}$ is $40 \mathrm{rad} \mathrm{s}^{-1}$.
(b) Its angular velocity at $4 \mathrm{~s}$ is $42 \mathrm{rad} \mathrm{s}^{-1}$.
(c) Its angular acceleration is $10 \mathrm{rad} \mathrm{s}^{-2}$.
(d) During the first 1 s it makes $\frac{2.5}{\pi}$ revolution.