How do you explain the effect of air resistance using Newton's Laws of Motion?

Question

In a question, a pebble and a feather both have the same mass (and so the same weight), but the feather reaches terminal velocity quicker than the pebble. How would you explain that using Newton's Laws?

Answer 1

The feather is wider and has to push a larger amount of air out of its way while falling, which requires more force. The faster the feather falls, the faster the air has to get out of the way, which means it has to be accelerated away, via F=ma. At some point, the force required to accelerate this air out of the feather's way balances the force of gravity. The same happens for the pebble, but since it's smaller, a smaller amount of air has to be accelerated, so the force is small until the pebble is falling so fast that air has to be accelerated out of its way very quickly (large a) and so it also reaches a terminal velocity, but a faster one.

Answer 2

It's pretty simple, An object in motion , stays in motion until acted on by a greater or equal force. The force is resistance, which are atoms and molecules in the air (basically what air is), A feather has much more surface exposure to get caught up on all those atoms and molecules then the pebble, the pebble is able to create a wedge-like effect and displace the 'Air' more uniformly. Of coarse we are assumimg the pebble and feather are the same weight.

Answer 3

Third law of motion says that for each action there is an equal and opposite reaction. As something is moving through air, it is pushing the air out of the way, but the air is pushing back with an equal and opposite amount of force, thus air resistance. A feather is shaped to catch the air and hold onto it, increasing air resistance, while a pebble is shaped where the air will flow around it much more easily then a feather, thus less air resistance.