Question

Why does deploying a parachute slow down a skydiver?

A. Parachutes provide air drag. Once the parachute was deployed the resulting air drag caused the skydiver to actually start going upwards. So in fact, the skydiver doesn't slow down but starts traveling upwards until gravity overcomes the air drag and brings the skydiver safely to the ground. This is why the skydiver slows down.

B. At the moment the parachute is deployed the skydiver is moving fast. The high speed combined with the sudden increase in surface area drastically increases the air drag on the skydiver and as a result the air drag is greater than the skydiver's weight. Thus, the skydiver's acceleration and velocity are in opposite directions and hence the skydiver will slow down.   

C. Parachutes catch the air. This decreases the overall density of the skydiver. Low density objects, such as feathers, do not fall straight down but rather float to the ground.

D. When the parachute is deployed, the bag on the skydiver's back becomes lighter. Hence, the skydiver is lighter. As a result, the skydiver slows down.

E. Parachutes are specially designed to exhibit anti-gravity. It is this property of the parachute that causes the skydiver to slow down.

Answer 1

When the objects fall through the earth's atmosphere, they tend to increase the velocity until the upward air drag balances the downward gravitational pull. When these forces balance each other, the object fall with a constant velocity called terminal velocity.

Larger the surface area and velocity of an object, larger is the air drag.

For a sky diver falling with high velocity, opening of a parachute results in a sudden increse in the surface area, causing the air drag to increase by a much larger amount. This result in a smaller value of terminal velocity, thereby slowing down the parachutist.

So, option B is correct.