Question

A rocket accelerates straight up by ejecting gas downwards. In a small time interval Δt, it ejects a gas of mass

Answer 1

A rocket accelerates straight up by ejecting gas downwards. In a small time interval Δt, it ejects a gas of mass Δm at a relative speed u. Calculate KE of the entire system at t + Δt and t and show that the device that ejects gas does work = (1/2)Δmu2 in this time interval (neglect gravity).

Answer:

Check this attachment :-)

ejects gas does work = (1/2) Δmu2 in this time interval