Question

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

Answer 1

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.

Answer 2

Ans: 14.9 m

The height from which the ball is dropped  = 20 m

Velocity of the ball the = 10 m/s

Kinetic energy, KE = 1/2mv²

Potential energy, PE = mgh

The height at which KE = PE is

1/2mv² = mgh

v² = 2gh

h = v²/2g = (10)²/2(9.8) = 5.1 m

Height from the ground = 20-5.1 = 14.9 m