Question

A gun of mass M fires a bullet of mass m with a horizontal speed V. The gun is fitted with a concave mirror of focal length f facing towards the receding bullet. Find the speed of separation of the bullet and the image just after the gun was fired.

Answer 1

Recoil velocity of gun = V_g =mV/M.

At any time ‘t’, position of the bullet w.r.t. mirror

Since, the mirror itself is moving at a speed of mV/M and the object is moving at ‘V’, the velocity of separation between the image and object at any time ‘t’ will be,