Momentum

Step 1: Apply conservation of momentum.
Since there are no external forces, the total momentum of the system must remain zero.
Initially, both the boy and the ball are at rest, so the initial momentum is zero.

Step 2: Use the momentum formula.
The momentum before and after the throw must satisfy: Substitute the known values: Solving for , we get: Since the center of mass speed is the average velocity of the system, it will be zero because the boy's movement cancels the ball's momentum.