a student throws a 0.130kg ball straight upwards to a height of 7.70m. how much work did the student do?
well how much potential energy does the ball have when it reaches the top compared to the bottom? (I am assuming that you mean the ball ran out of kinetic energy and stopped at h = 7.70 meters)
U = m g h = 0.130 * 9.81 * 7.70 = 9.82 Joules
That potential energy was totally provided by the student in the form of work done throwing it up.
work in = kinetic energy gained = potential energy at peak