# Thread: Impulse with wall and change of direction

1. ## Impulse with wall and change of direction

Got an impulse question here that I wouldn't normally struggle with, however there's something about a change of direction and not sure what to do here?

A ball of mass 0.1 kg hits a wall at 15 m/s and rebounds at a speed of 5 m/s.

If the path of the ball's diverted by $\frac{\pi}{2}$ radians by the impact, find the magnitude of the impulse exerted on the ball by the wall.

$I = m(v_2 - v_1)$

$I = 0.1(-5 - 15) = -20$, so the magnitude of the impulse would be $20 Ns$?

Think that's right anyway. However I'm not sure how I'd solve it with the change of direction involved?

2. If you use vector subtraction, $|m(v_2 - v_1)| = m\sqrt{5^2 + 15^2}$ since the ball bounces at a right angle. This gives the magnitude of the impulse to be $$1.581 N \cdot s.$$ I'm not sure if this is the correct way to do the problem, but it does account for the change in direction.