1 Two particles \(P\) and \(Q\), of masses \(m \mathrm {~kg}\) and 0.3 kg respectively, are at rest on a smooth horizontal plane. \(P\) is projected at a speed of \(5 \mathrm {~ms} ^ { - 1 }\) directly towards \(Q\). After \(P\) and \(Q\) collide, \(P\) moves with a speed of \(2 \mathrm {~m} \mathrm {~s} ^ { - 1 }\) in the same direction as it was originally moving.

1. Find, in terms of \(m\), the speed of \(Q\) after the collision.
   After this collision, \(Q\) moves directly towards a third particle \(R\), of mass 0.6 kg , which is at rest on the plane. \(Q\) is brought to rest in the collision with \(R\), and \(R\) begins to move with a speed of \(1.5 \mathrm {~ms} ^ { - 1 }\).
2. Find the value of \(m\).