At time $t=0$ a grinding wheel has an angular velocity of $27\mathrm{.}0ra\frac{d}{s}.$ It has a constant angular acceleration of $26\mathrm{.}0ra\frac{d}{s^2}$ untli a circuit breaker trips at time $t=1\mathrm{.}90s.$ From then on$,$ the wheel turns through an angle of $440$ rad as it coasts to a stop at constant angular deceleration.