A 2kg marble is moving at 3 m/s when it strikes another 4kg marble moving in the opposite direction at - 3 m/s. What will be the velocity of the 4kg marble after the collision of the 2kg marble's new velocity is - 4 m/s. Also state the direction of the 2kg marble after they hit.

Momentum is conserved after the collision

Momentum of 2 Kg before collision = 2 * 3 = 6

Momentum of 4 kg before collision = 4 * - 3 = - 12

so 6 + - 12 = 2 * - 4 + 4 * x where x is velocity of 4kg marble.

4x - 8 = - 6

4x = 2

x = 0.5

Velocity of 4 kg marble is 0.5 m/s after collision

The 2 kg marble will move in the opposite direction to which it was moving before the collision.