Explore: What is drag?

If you drop a rock and a feather at the same time, which falls faster?

What if you were to drop the same rock and the same feather on the moon? Would you be surprised to find out that they both fall at the same rate?  The air on Earth produces air resistance or drag, which allows the feather to fall slower than the rock. On the moon, there is no air to slow down the feather, so both the feather and rock will hit the ground at the same time.  This website explains why.

 

A parachute is a device used to slow down an object that is falling towards the ground.

There are two forces acting on the falling person:

• Gravity
  
• Air resistance

Without a parachute, the gravity is more than air resistance. However, as the parachute opens, the air resistance increases. Now, air resistance is more than gravity.

This slows down the parachute and the person can land safely on the ground. 

• A heavier load, will make the parachute fall faster. 
• The spill hole in the top of the canopy of the parachute stabilizes it. The hole lets air escape out the top rather than spilling out one side and then the other.
  

  Video

Drag can be useful when something is trying to slow down. Birds use their wings to produce drag for slowing down or landing.  Parachutes use drag to allow things to land slower to reduce the impact.

Drag makes it difficult for things to move quickly.  Airplanes and race cars are designed to allow air to flow easily past, so that air resistance is reduced. The amount of drag on an object can be changed by changing its shape or speed.

You can experience drag as you move through the air or the water.  In this activity, you will explore how to change the amount of drag you encounter.

  Check Your Answers

  Astronomy Connection

This animation shows how parachutes were used to produce drag during the landing of the Mars Rover. Slowing the landing was essential to reduce the impact and possible damage to the rover when it landed on Mars.