Question

A ball of mass 50 g moving with a speed of 2.0 m s strikes a wall at an angle of incidence 45

Answer 1

here is your answer

let ball is moving in x-y plane & approaching a wall at an angle45 degree which is placed in y-z plane...

initial momentam of ball is Pi =mvcos45 i + mvsin45(-j)

finally it returnes at same angle & with same velocity so its final momntam is

Pf = mvcos45(-i) + mvsin45(-j)

change in momentam= Pi - Pi =2mvcos45

=21/2 mv

=100.21/2 or 100sqrt2 ans