Average Force on a Rocket During Gas Exhaustion

[subopolois]

Homework Statement

Rocket engine expends 1150 kg of gas in 1 second, with a velocity of -4.50×10^4 m/s. Calculate the average force exerted on the rocket by the gas during that 1.0 second interval

Homework Equations

F= m(delat)v / (delta)t

The Attempt at a Solution

F= (1150kg)(-45000m/s) / 1 s
-5.175 x 10^7 N

 

[mfb]

I would use a different sign for deltam, but apart from that it is right.

 

[rude man]

Homework Statement

Rocket engine expends 1150 kg of gas in 1 second, with a velocity of -4.50×10^4 m/s. Calculate the average force exerted on the rocket by the gas during that 1.0 second interval

Homework Equations

F= m(delat)v / (delta)t

The Attempt at a Solution

F= (1150kg)(-45000m/s) / 1 s
-5.175 x 10^7 N

Your answer is OK except no - sign. The problem implicitly asks for a magnitude.
But, you should give a bit more detail on why that formula works, starting with conservation of momentum of the rocket/gas system:
force x 1 sec. = change per second in momentum of rocket = - change per second in momentum of the gas
etc.