A 5000 kg rocket is set for vertical firing. The exhaust speed is 800 ms -1. To give an initial upward acceleration of 20 ms -2, the amount of gas ejected per second to supply the needed thrust will be (g=10 ms -2)

Question

A 5000 kg rocket is set for vertical firing. The exhaust speed is 800 ms -1. To give an initial upward acceleration of 20 ms -2, the amount of gas ejected per second to supply the needed thrust will be (g=10 ms -2) (A) 137.5 kgs -1 (B) 185.5 kgs -1 (C) 127.5 kgs -1 (D) 187.5 kgs -1

Tardigrade Admin · Accepted Answer

Thrust =M(g+a)=u (d m/d t) (d m/d t)=(M(g+a)/u)=(5000(10+20)/800) =187.5 kg / s

Q. A $5000 k g$ rocket is set for vertical firing. The exhaust speed is $800 m s^{- 1}$ . To give an initial upward acceleration of $20 m s^{- 2}$ , the amount of gas ejected per second to supply the needed thrust will be $(g = 10 m s^{- 2})$

$137.5 k g s^{- 1}$

$185.5 k g s^{- 1}$

$127.5 k g s^{- 1}$

$187.5 k g s^{- 1}$

Thrust $= M (g + a) = u \frac{d m}{d t}$
$\frac{d m}{d t} = \frac{M ( g + a )}{u} = \frac{5000 ( 10 + 20 )}{800}$
$= 187.5 k g / s$

Q. A 5000kg rocket is set for vertical firing. The exhaust speed is 800ms−1. To give an initial upward acceleration of 20ms−2, the amount of gas ejected per second to supply the needed thrust will be (g=10ms−2)

137.5kgs−1

185.5kgs−1

127.5kgs−1

187.5kgs−1