A body is thrown vertically upward inside a lift with velocity u relative to the lift. Its time of flight relative to the lift is t. The upward acceleration a of the lift is:
Options

Question

A body is thrown vertically upward inside a lift with velocity u relative to the lift. Its time of flight relative to the lift is t. The upward acceleration a of the lift is:

G1 Physics · Accepted Answer

Relative downward acceleration of the body with respect to the lift is g+a. For return to the same point, t=2u/(g+a). Hence g+a=2u/t, so a=(2u-gt)/t. Option B.