Question

question 10 of 25
a parachutist of mass 100 kg falls from a height of 500 m. under realistic conditions, she experiences air resistance. based on what you know about friction, what can you say about the kinetic energy of the parachutist as she reaches the ground? remember, 1 kj = 1000 j. acceleration due to gravity is g = 9.8 m/s².

a. ke>490 kj
b. ke = 0 j
c. ke = 490 kj
d. ke<490 kj

Explanation:

Step1: Calculate potential energy

The potential energy formula is $PE = mgh$. Given $m = 100\ kg$, $g=9.8\ m/s^{2}$, $h = 500\ m$. So $PE=100\times9.8\times500 = 490000\ J=490\ kJ$.

Step2: Consider air - resistance effect

Air - resistance is a non - conservative force. It does work against the motion of the parachutist, dissipating some of the initial potential energy as heat and other forms of energy. So the kinetic energy of the parachutist when she reaches the ground is less than the initial potential energy.

Answer:

D. $KE<490\ kJ$