Step 1:

The mass of a tennis ball is .

The velocity of the ball is .

The ball strikes a wall with an angle is .

The initial momentum along the -axis: . \ \ \ \ The final momentum along the -axis: . \ \ The impulse along the -axis: .

. \ \ \ \ The initial momentum along the -axis: .

The final momentum along the -axis: . \ \ \ \ The impulse along the -axis: .

The impulse is .

Substitute and .

.

The magnitude of the impulse is .

The impulse has negative sign it indicates that the direction of the ball after impulse is downwards. \ \

- 6.9 kg m/s is the impulse or the change of momentum in the  ball after hit.

\ \ \ \ J = Jx = -2mvcos(45) = -2*0.05*70*cos(45) = - 4.95kgm/s