A 70.0 kg person jumping down from a 3.00 meter wall hits the ground at 7.70 m/s. He hits the ground with stiff legs and stops in 0.023 seconds. What is the force of impact, in newtons?

Idon’t quite understand this problem

Explain why electric current cannot exist if a current doesn't have a voltage source.

Amass weighing 24 pounds, attached to the end of a spring, stretches it 4 inches. initially, the mass is released from rest from a point 8 inches below the equilibrium position. find the equation of motion. (use g = 32 ft/s2 for the acceleration due to gravity.)