Answer:
The ball was thrown at approximately \(19.6m/s\).
Explanation:
Assuming that there is no air resistance (or drag) in this question, the time to go up is the same to go down. Therefore, we can assume that it takes 2 seconds to go up and then 2 seconds to go down (4 seconds in total).
On Earth's surface, gravity is approximately \(9.8m/s^{2}\). Notice the \(s^{2}\) meaning that gravity is given in terms of acceleration. As it's an acceleration, it means that velocity changes at a rate of 9.8 meters per second. As we have 2 seconds of deceleration going up, we have a starting speed of \(2 * 9.8m/s\) = \(19.6m/s\) .
