Two particles, P and Q, have masses 2m and 3m respectively - Edexcel - A-Level Maths Mechanics - Question 2 - 2017 - Paper 1

The direction of motion of P has been reversed by the collision. This is evident since the speed of P after the collision is now equal to u, indicating a change in its direction.

Impulse can be determined from the change in momentum of particle P. The impulse exerted on P by Q is given by:

$I = ext{Change in momentum} = m(v_{final} - v_{initial})$

Using the values for P:

Initial momentum before the collision: $p_{initial} = 2m(4u) = 8mu$ Final momentum after the collision: $p_{final} = 2m(u) = 2mu$

Now calculating the impulse:

$I = 2mu - 8mu = -6mu$

The magnitude of the impulse, which is the absolute value, is:

$|I| = 6mu$

Therefore, the magnitude of the impulse exerted on P by Q in the collision is 6mu.