An 80-kg person falls out of an airplane and eventually reaches maximum speed (terminal velocity). We estimate the force of air friction at this speed to be
A) 780 N.
B) 0 N.
C) 22 N.
D) 52 N.

Question

Quizplus · Accepted Answer

At terminal velocity, the force of air friction equals the gravitational force acting on the person. The gravitational force can be calculated as $F = m \cdot g$, where $m = 80 \, \text{kg}$ and $g \approx 9.8 \, \text{m/s}^2$. Thus, $F = 80 \, \text{kg} \cdot 9.8 \, \text{m/s}^2 = 784 \, \text{N}$, which is approximately 780 N, indicating that the force of air friction must balance this to maintain terminal velocity.

An 80-Kg Person Falls Out of an Airplane and Eventually