Question

A ball of mass 20g hits a wall at an angle 45 with velocity of 15m/s.if ball rebounds at 90 to direction of incidence,calculate impluse received by ball

Answer 1

Let's consider the momentum vectors before & after hitting. 
As we know, 
Impulse=Change in momentum 
I=mv'-mv 
=(mvcos45+mvsin45)-(mvcos45-mvsin45) 
[since, vertical resolution cancel out and horizontal adds up] 
=2mvsin45 
=2*0.02*15*sin45 
=0.424 N-s

Answer 2

❒$\: \sf m=20g=0.02kg$

❒$\:\sf v=15m/s$

$\sf impulse \: is \: given \: by \: momentum\: change=m.Δv$

$\sf =m.( v_{f}- v_{i}) \sin(∅)$

$\sf = 0.02(-15-15) \sin45°$

$\sf = 0.042kg.m/s$