Question

A ball rolls over the edge of a platform with only a horizontal velocity. The height of the platform is 1.6 m and the horizontal range of the ball from the base of the platform is 20 m. What is the horizontal velocity of the ball just before it touches the ground? Neglect air resistance. Use g = -9.8 m/s2.

Answer 1

35 m/s

Explanation:

Let gravitational acceleration g = 9.8m/s2. We can calculate the amount of time for the ball to fall vertically a distance of 1.6 m

`1.6 = 9.8t^2/2`

`t^2 = 2*1.6/9.8 = 0.327`

`t = √(0.327) = 0.571s`

This is also the time it takes for the ball to fly horizontally, assume constant horizontal speed, we can calculate the speed it takes to travel across 20m in 0.571s

v = 20 / 0.571 = 35 m/s