A rock, mass = 2.0 kg, is fired straight up at 60 m/s from a catapult. What will be its maximum height at the moment it stops going up and starts to come down? Use the magnitude of g to be -10m/s2.

Answer 1

Use the potential energy and momentum.
mommentum = mass times velocity
So 2kg x 60m/s
Take that answer and set it equal to the formula for potential energy. This works because when the rocks velocity is zero all the energy will be converted from kinetic energy to potential energy.
So 2kg x 60m/s= 2kg x gravity x h.
And your height will be the moment it is at the absolute top of its height.