# Average acceleration

A ball is dropped from 4 ft and rebounds back to 3 feet. If the ball was in contact with the ground for 0.01 seconds, then what is the average acceleration of the ball during contact? The answer on the back of the book is 3000 ft/sec^2. So average acceleration is defined as $$\frac{\Delta V}{\Delta t}$$. So $$\frac{x}{0.01}$$. Then $$\Delta V = 30$$. How would you get 30?

Thanks

OlderDan
Homework Helper
You need to calculate the speed at impact for a ball dropped from 4 feet, and the speed it would need to have when leaving the floor to rise to a height of 3 feet. Take the difference between the two velocities (speed and direction) to get $$\Delta V$$

HallsofIvy