Given that VB =2u, show that e=3/5

Step 1: Set up the equations for conservation of momentum and the coefficient of restitution.
Let the initial direction of particle A be positive.

• Mass of particle A: $m_A = m$
• Mass of particle B: $m_B = 3m$
• Initial velocity of particle A: $u_A = 4u$
• Initial velocity of particle B: $u_B = -u$ (since they are moving towards each other)
• Final velocities: $v_A$ and $v_B$

Conservation of momentum:

$$m_A u_A + m_B u_B = m_A v_A + m_B v_B$$ $$$$