Question

A 4.0 kg model rocket is launched, shooting 50.0 g of burned fuel from its exhaust at an average velocity of 625 m/s. What is the velocity of the rocket after the fuel has burned?

Answer 1

Velocity of rocket will be equal to 7.81 m/sec

Step-by-step explanation:

We have given mass of the rocket
`m_1=4kg`

Mass of fuel is given
`m_2=50gram=0.05kg` ( As 1 kg is equal to 1000 gram )

Velocity of fuel
`v_2` = 625 m/sec

We have to find the velocity of rocket
`v_1`

From conservation of momentum we know that initial momentum is equal to final momentum '

So
`m_1v_1=m_2v_2`, here
`m_1` is mass of rocket
`v_1` is velocity of rocket
`m_2` is mass of fuel and
`v_2` is velocity of fuel

So
`4* v_1=625* 0.05`

`v_1=7.81m/sec`

So velocity of rocket will be equal to 7.81 m/sec