Question

A body A of mass 1.5kg, travelling along the positive x-axis with speed 4.5m/s, collides with
another body B of mass 3.2kg which, initially, is at rest. As a result of the collision, A is deflected and
moves with a speed 2.1m/s in a direction which is at angle 30° below the x-axis. B is set in motion at an
angle θ above the x-axis. Calculate the velocity of B after the collision.

Answer 1

Momentum in x-axis before collision: 4.5 x 1.5 = 6.75

Momentum in x-axis after collision: 1.5 x 2.1 x cos(30) + 3.2 x v x cos(30)

By the principle of conservation of momentum, these are equal:
6.75 = 2.73 + 2.77v
v = 1.45 m/s