I am doing my HW and I have a few questions I don't understand. Each has their own answers but I have to find how they got it...
#3 How much kinetic energy must an 80-kg high jumper generate to move his center of mass from 0.9m above the ground to clear the bar, which is 2.1m aboce the ground ( ans: KE= 960J)
The difference in gravitational potential energy in the starting position and the final height is what determines the KE.
difference in PE=mass(g)(2.1-.9)
= 80*9.8*1.2 Joules