Two particles B and C have mass m kg and 3 kg respectively - Edexcel - A-Level Maths Mechanics - Question 1 - 2011 - Paper 1

To find the mass of particle B, we apply the principle of conservation of momentum. Before the collision, the momentum of the system can be expressed as:

$P_{initial} = m imes 4 + 3 imes (-2)$

Here, the speed of C is negative since it is moving in the opposite direction. After the collision, the momentum is:

$P_{final} = m imes 1 + 3 imes 3$

Setting the initial momentum equal to the final momentum gives us:

$m imes 4 - 6 = m imes 1 + 9$

Rearranging this equation gives:

3m = 15 \ m = 5$$ Thus, the value of m is 5 kg.