Air and water resistance

In a nutshell

Both air and water resistance are examples of friction, they slow down a moving object. Air resistance slows down an object moving in the air and water resistance slows down an object moving in water.

Air resistance

This is a type of friction that acts between the air and an object moving through it. It works in the opposite direction to the one that the object is moving in.

An object with a greater surface area will experience more air resistance, and so it will fall more slowly than an object with less surface area.

Example

If a feather and marble are dropped next to each other, the feather will take more time to reach the ground than the marble. This is because the feather has a larger surface area, so it experiences more air resistance.

This means that it is slowed down much more than the marble and therefore takes longer to reach the ground. The marble experiences much less air resistance because of its smaller surface area.

If there was no air resistance, they would both hit the ground at the same time because the force of gravity is the same.

Science; Forces; KS2 Year 5; Air and water resistance

1	Air resistance
2	Gravity

Water resistance

This is a type of friction that acts between water and an object moving through it. Once again, a larger surface area will mean that the object is slowed down more. This force also works in the opposite direction to the one the object is moving in.

Example

A swimmer will experience water resistance as they swim through water. As the swimmer moves forward, water resistance will push back in the opposite direction. This will mean they will move more slowly than if there was no water resistance.

In order for the swimmer to keep swimming, they must swim with a greater force than the water resistance, otherwise they will not be able to move forward.

Science; Forces; KS2 Year 5; Air and water resistance

1	Water resistance