Question

A student throws a ball upwards from the ground level where gravitational potential energy is zero. At a height of 15 m, the ball has a potential energy of 60 J, and is moving upwards with a kinetic energy of 40 J. Ignoring air resistance, the maximum height achieved by the ball is most nearly

Answer 1

PE = 60 = m g h = k * 15 ... k = 4

the KE will become PE as the ball rises ... 4 J per meter of height
... the ball will rise another 10 m

Answer 2

20