Question

A particle of mass m is moving with speed u in a direction which makes 60° with respect to x axis. It undergoes elastic collision with the wall. What is the change in momentum in x and y direction?

Answer 1

\(Δ p_x = -2mu, Δ p_y = 0\)

The change in momentum of the molecule in x direction 

\(Δ p_x\) = Final momentum - Initial momentum,

= After collision - Before collision

= -mu - mu = -2mu

Then change in momentum of the molecule in Y direction \(Δ p_y\)= 0