Discussion Forum

A 5000 kg rocket is set for vertical firing. The exhaust speed is 800 m/s. To give an initial upward acceleration of 20 m/s², the amount of gas ejected per second to supply the needed thrust will be (Take g = 10 m/s²)

Answer:

Explanation:

Given :

Mass of rocket (m) = 5000 Kg

Exhaust speed (v) = 800 m/s

Acceleration of rocket (a) = 20 m/s²

Gravitational acceleration (g) = 10 m/s²

We know that upward force

F = m (g + a) = 5000 (10 +20) = 5000 x 30 = 150000N.

We also know that amount of gas ejected

$\frac{dm}{dt}=\frac{F}{V}=\frac{150000}{800}$=187.5kg/s