Question

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)(a) 127.5 kg/s (b) 137.5 kg/s(c) 155.5 kg/s (d) 187.5 kg/s

Answer 1

Mass of rocket(M)= 5000 kg

Exhaust speed(v)=800m/s^2

Acceleration(a)=20m/s^2

acceleration due to gravity (g)=10 m/s^2

F=m(g+a)=5000(10+20)=15000N

amount of gas ejected per second= F/v=15000/800=187.5 kg/s

Answer 2

Answer:

We know that F=m(g+a)

=5000(10+20)

=5000×30

=150000N

 

Amount of gas ejected per second=F/V

150000/800

=187.5kg/s