When a motor cyclist takes a `U-turn` in `4s` what is the average angular velocity of the motor cyclist.

Explanation

When the motor cyclist takes a U-turn, angular displacement, `theta=pi` rad and `t=4s`.
The average angular velocity,
`omega=theta/t,alpha_(av)=(Deltaomega)/(Deltat)`
`omega=(d theta)/dt,alpha=(d omega)/dt=(d^(2)theta)/dt^(2)=omega(domega)/(d theta)`
int d theta=int omega dt, int d omega=int alpha dt,int alpha d theta=int omega d omega`