A ball moving with a momentum of `5kg ms^(-1)` strikes against a wall at an angle of `45^(@)` and is reflected at the same angle calculate the angle in momentum

Explanation

Initial momentum is along AO. It has two rectangular components

P cos `45^(@)` along CO and P sin `45^(@)` along DO final momentum P is alon OB. It has two rectangular components.
Change in momentum along vertical direction =final momentum - Initial momentum = P sin `45^(@)- P sin 45^(@) =0`
Change in momentum along horizotal direction
`=- P cos 45^(@) - cos 45^(@)`
`=-2xx 5 xx (1)/(sqrt(2))`
`=-7.07 kg ms^(-7)`
Negative sign indicates that the direction of changes in momentum is away from the wall.