The first stage of a space vehicle consumed fuel and oxidizer at the rate of 1.75 ✕ 104 kg/s, with an exhaust speed of 2.70 ✕ 103 m/s.

(a) Calculate the thrust produced by these engines.
N
(b) Find the acceleration of the vehicle just as it lifted off the launch pad on the Earth if the vehicle's initial mass was 3.00 ✕ 106 kg. [Note: You must include the force of gravity to solve part (b).]
m/s2 upward

1 answer

Force up = rate of change of momentum
Per second momentum back = 1.75*2.7 * 10^7
= (4.73 *10^7 kg m/s)/s = 4.73*10^7 Newtons

F = m a
Fup - m g = m a
a = Fup/m - g
= 4.73*10^7/3*10^6 - 9.81
= 47.3/3 - 9.81