Find in terms of u and e the speeds of A and B after impact.

You're right to check your work! Let's go through it step-by-step to find the correct expressions for $v_A$ and $v_B$.

Let $m_A = m$ and $m_B = 3m$ be the masses of spheres A and B, respectively.
Let $u_A = 4u$ and $u_B = -u$ be their initial velocities (taking the direction of A as positive).
Let $v_A$ and $v_B$ be their velocities after impact.

i) Find in terms of $u$ and $e$ the speeds of A and B after impact.

Step 1: Apply the principle of conservation of momentum.

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