The mass of a rocket is 500kg and the relative velocity of gases ejecting from it is `250ms^(-1)` with respect to the rocket. Find the rate of burning of the fuel to give the rocket an initial acceleration of 20 `ms^(-2)` in the vertically upwards direction. (take `g=10ms^(-2)`)

Options

A. `300 kg s^(-1)`
B. `60 kg s^(-1)`
C. `90 kg s^(-1)`
D. `30 kg s^(-1)`

Answer

B

Explanation

Here `m= 500kg, u= 250 ms^(-1), a= 20 ms^(-2), g= 10ms^(-2)`
Thrust required, `m(a+g)= u(dm)/(dt), (dm)/(dt)= 60kg//s`