Question

A rocket is moving vertically upward against gravity. Its mass at time t is `m=m_0-mut` and it expels burnt fuel at a speed u vertically downward relative to the rocket. Derive the equation of motion of the rocket but do not solve it. Here, `mu` is constant.

Answer 1

Correct Answer - B::D
`(-(dm)/(dt))=mu`
`F_(n et)="thrust force" -"weight"`
`:. ma=v_r(-(dm)/(dt))-mg`
or `(m_0-mut)(d^2x)/(dt^2)=u(mu)-(m_0-mut)g`