# physics

posted by Anonymous

A rocket engine on a spacecraft of total mass 10,000kg ejected 1.4kg of hot gases every second at an average discontinuous speed of 240ms-1.
1- What was the force on the spacecraft?

2- What was the acceleration of the spacecraft?

3-If the engines were used for 30's, what was the impulse given to the spacecraft?

4- What was the change of velocity?

1. Damon

force = rate of change of momentum

change of momentum of vehicle + change of momentum of fuel = 0

in one second:
10,000 (change of vehicle speed) = 1.4*240 = 336 kg m/s
so
change of vehicle momentum per second =336 kg m/s^2 = Force (answer #1)

acceleration = change of vehicle speed per second = 336*10^-4 =3.36*10^-2 m/s^2

impulse = change of momentum in 30 seconds = Force * 30

change of velocity = change of momentum / mass

2. anonymus

so for change of momentum = 336 divided by 10,000? @Damon

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