A ball is dropped from a height of 20 meters. At what height does the ball have a velocity of 10 meters/second?

Base on your question where there is a ball dropped from a height of 20 meters so to get the height of the ball that has a velocity of 10m/s, first is you must consider the gravitational force of the ball which is 9.8m/s^2. With that reason it self the ball from 0 velocity when drop has a 9.8 m/s^2 velocity os i think the height could e 10.2 m by rounding up the velocity.