Question

Two balls, A and B, are launched horizontally at the same time from the same height.  Ball A is launched with an initial speed of 12.6 m s-1 and lands 23.2 m away.  Ball B lands 56.4 m away.

1. How high were the balls launched from?
2. How fast was ball B launched at?

Answer 1

The height is

$$h=gt^2/2=g/2·(R_A/v_A)^2=16.6\text{ m}.$$

The speed of the second ball is

$$v_B=R_B\sqrt{\frac{g}{2h}}=30.6\text{ m/s}.$$