Question
A rocket is fired vertically from the ground. It moves upward with a constant acceleration 10 m/s2 for 30s after which the fuel is consumed. After what time from the instant of firing the rocket will attain the maximum height?
Joshi sir comment
total height covered in upward journey = at2/2 = 10*30*30/2 = 4500 = 4.5 km
after consuming all the fuel, it will fall with gravity and g = 10 m/s2 so it will move the same distance again upto stop
so max H = 9 km.