A parachutist of mass 50.0 kg jumps out of an airplane at a height of 800 m.The parachute deploys,and she lands on the ground with a speed of 5.0 m/s.How much energy was lost to air friction during this jump?

Question

Quizplus · Accepted Answer

The initial potential energy of the parachutist at a height of 800m can be calculated using the formula: 
PE = mgh = (50.0 kg)(9.8 m/s^2)(800 m) = 392,000 J

The final kinetic energy of the parachutist can be calculated using the formula: 
KE = (1/2)mv^2 = (1/2)(50.0 kg)(5.0 m/s)^2 = 625 J

The energy lost to air friction during the jump is equal to the difference between the initial potential energy and the final kinetic energy: 
Energy lost = PE - KE = 391,000 J

Therefore, the best choice is C.

A Parachutist of Mass 50