Question

A rocket has a mass of 21000 kg of which 15000kg is fuel. The rocket engine can exhaust fuel att
rate of 190kg s- with an exhaust velocity 2500ms-' relative to the rocket. If the rocket is fire
vertically upwards, its final velocity at the burn out is (in ms-) (given In (3.5) = 1.253]
1) 2358
2) 2935
3) 2535
4) 1975​

Answer 1

Answer:

Velocity of rocket is given as

v=u ln(M/M-rt)

wher M is the total mass of rocket + fuel at t=0 sec = 20 +180 =200 kg

and r rate of fuel consumption =2kg/sec

u is the velocity of gas ejection w.r.t rocket = 1.6 km/sec

ultimate velocity is achieved when all the fuel will burn

ie. M-rt =20 kg

so v= 1.6 ln(180/20)

=3.515 km/sec

Hope it 8s correct because I am not very good in maths

Explanation:

Answer 2

Answer:

Explanation:

Intial mass m = 21000kg

Mass of fuel = 15000kg

Final mass of rocket m = 6000kg

-dm/dt = 190kg/s

Vr =2500m/s

V = U+Vr(Ln(Mo/m))-9t

Time (t) = mass of fuel/dm/dt

T = 15000/190

T = 1500/19

V = U + Vr(Ln(Mo/m))-9t

V=2500(Ln(3.5))-789.4 = 2342.5 m/s