Question

A 10 kg gun recoils with a speed of 0.1 m/s after it fires a 0.001 kg bullet. What is the speed of the bullet?

Answer 1

As we know that here gun + bullet system is isolated from all other external force system

so here the momentum of system is always conserved

so we will say

`m_1v_(1i) + m_2v_(2i) = m_1v_(1f) + m_2v_(2f)`

here we know that

`v_(1i) = v_(2i) = 0`

`m_1 = 10 kg`

`m_2 = 0.001kg`

`v_(1f) = 0.1 m/s`

now we will have

`0 + 0 = 10(0.1) + 0.001v_(2f)`

by solving above equation we will have

`v_(2f) = 1000 m/s`