Question

A 7.0kg skydiver is descending with a constant velocity

Answer 1

Answer:

The air resistance on the skydiver is 68.6 N

Explanation:

When the skydiver is falling down, there are two forces acting on him:

- The force of gravity, of magnitude $mg$, in the downward direction (where m is the mass of the skydiver and g is the acceleration due to gravity)

- The air resistance, $R$, in the upward direction

So the net force on the skydiver is:

$F=mg-R$

where

m = 7.0 kg is the mass

$g=9.8 m/s^2$

According to Newton's second law of motion, the net force on a body is equal to the product between its mass and its acceleration (a):

$F=ma$

In this problem, however, the skydiver is moving with constant velocity, so his acceleration is zero:

$a=0$

Therefore the net force is zero:

$F=0$

And so, we have:

$mg-R=0$

And so we can find the magnitude of the air resistance, which is equal to the force of gravity:

$R=mg=(7.0)(9.8)=68.6 N$