Physics - Kinematics Question with Solution | TestHub

A helicopter takes off along the vertical with an acceleration $a=3m/s^2$ and zero initial velocity. In a certain time $t_1$, the pilot switches off the engine. At the point of take off, the sound dies away in a time $t_2=30\sec$. Determine the velocity of the helicopter at the moment when its engine is switched off assuming that velocity of sound is 320 m/s.