How much air resistance acts on a falling 100-N box of nails when it reaches terminal velocity?

1 Answer
Aug 29, 2017

$100$ $\text{N}$

Explanation:

For simplicity's sake, let's assume that only two forces are acting on the box of nails: the $100$ $\text{N}$ weight of the box (the force of gravity) and air resistance.

Now, if the box of nails reaches terminal velocity, it will travel at a constant velocity.

Travelling at a constant velocity means that the box will no longer accelerate, so no more force will be applied to it (according to Newton's second law of motion).

Following the law, the net force on the box must be equal to zero.

Therefore, if the weight of the box of nails is $100$ $\text{N}$, the amount of air resistance must also be $100$ $\text{N}$.

In other words, $\text{net force} = 100$ $\text{N}$ $- 100$ $\text{N} = 0$ $\text{N}$.