# Calculating the exhaust velocity using conservation of momentum [closed]

I was just wondering if i did this correctly

$$p_{exhaust}=-p_{rocket}$$ $$m_{e}v_{e}=-m_{r}v_{r}$$ $$v_{e}=\frac{-m_{r}v_{r}}{m_{e}}$$ I used data from a Saturn V simulation by Robert A. Braeunig to find out mass flow rate, $$m_{e}$$ and then used the instaneous mass of the rocket, $$m_{r}$$ and the respective velocity

Thanks.

• It's not clear what you are trying to do here, but the final equation looks wrong, because it ways that for a rocket sitting on the launch pad with $v_r = 0$, the exhaust velocity is also $0$ so the rocket is never going to take off! Jul 28 '19 at 14:17
• The change in momenta at any instant must balance, not the absolute momenta. You need the rocket equation. Try this description. Jul 28 '19 at 14:43