# Air Resistance

## Key Stage 2

### Meaning

Air Resistance is a force that slows objects down when they are moving through the air.

Noun: Air Resistance

### About Air Resistance

Air resistance is a contact force.
Air resistance can only happen to an object surrounded by air. It does not happen to objects underwater or in space.
The amount of air resistance depends on:
• The size of an object.
• The shape of an object.
• How fast an object is moving through the air.
 The van is smaller than the truck, so it feels less air resistance. The truck is bigger than the van, so it feels more air resistance.
 The scrunched up paper has a lot of air resistance and will slow down quickly when you throw it. The paper plane is streamlined so it does not have much air resistance and will keep going fast once you've thrown it.

 A spitfire can travel at a speed of 160 metres per second. A jet fighter can travel 6 times faster that a spitfire so it feels a lot more air resistance.

### Experiments

Air Resistance and Weight

Time how long it takes a single Cupcake case to fall from the ground from 1.5 metres high.
Repeat this for two, three, four and five cupcake cases stacked together.
This changes the weight without changing the shape of the object.
If the difference is too small for meaningful results try 2, 4, 6, 8 and 10 cases.
Plot the results on a Scatter Graph (not a line graph or bar chart).

Air Resistance and Shape

Cut several different shaped parachutes from bin liners.
Ensure that the surface area of all shapes is the same. This can support math skills calculating area of shapes.
Use string to attach the parachutes to the same piece of plastacine each time.
Plot the results on a Bar Chart (not a line graph or scatter graph).

Air Resistance and Size

Cut several different size parachutes from bin liners.
Ensure that the surface area of each parachute increases by the same amount each time. This can support math skills calculating area of shapes.
Use string to attach the parachutes to the same piece of plastacine each time.
Plot the results on a Scatter Graph (not a line graph or bar chart).

## Key Stage 3

### Meaning

Air Resistance is a force which acts to decelerate objects that are moving through the air.

### About Air Resistance

Air resistance is a force so it is measured in Newtons.
Air resistance is a contact force because it can only exist when an object is moving in the air.
Air resistance increases with speed. The faster you travel the greater the air resistance.
Air resistance depends on the surface area facing the direction of motion. The bigger the surface area, the larger the air resistance

### Examples

 As the bowling ball moves through the air the air resistance slows it down. A car engine must provide a constant force to stay at the same speed because the air resistance would cause it to slow down. On Earth the air resistance causes a tennis ball to have a terminal velocity as it falls but on The Moon there would be no air resistance because there is no air. If the plane engine cuts out the air resistance will cause it to decelerate.

## Key Stage 4

### Meaning

Air Resistance is a force which acts to decelerate objects that are moving through the air.

### About Air Resistance

Air resistance is a force so it is measured in Newtons.
Air resistance is a contact force because it can only exist when an object is moving in the air.
Air resistance increases with speed. The faster you travel the greater the air resistance.
Air resistance depends on the surface area facing the direction of motion. The bigger the surface area, the larger the air resistance
Air resistance exists because objects moving through the air collide with atoms and molecules in the air passing on some of its momentum which causes the object to lose momentum and therefore slow down.

### Examples

 As the bowling ball moves through the air the air resistance slows it down. A car engine must provide a constant force to stay at the same speed because the air resistance would cause it to slow down. On Earth the air resistance causes a tennis ball to have a terminal velocity as it falls but on The Moon there would be no air resistance because there is no air. If the plane engine cuts out the air resistance will cause it to decelerate.

### References

#### AQA

Air resistance, page 147, GCSE Physics; Third Edition, Oxford University Press, AQA'
Air resistance, page 211, GCSE Combined Science; The Revision Guide, CGP, AQA'
Air resistance, page 63, GCSE Physics; The Revision Guide, CGP, AQA'
Air resistance, pages 140-2, 146, 154, 158, GCSE Physics; Student Book, Collins, AQA'
Air resistance, pages 159-161, GCSE Combined Science Trilogy; Physics, CGP, AQA'
Air resistance, pages 20, 121, GCSE Physics, Hodder, AQA'
Air resistance, pages 209, 234-5, GCSE Combined Science Trilogy 2, Hodder, AQA'
Air resistance, pages 39, 190-192, GCSE Physics; The Complete 9-1 Course for AQA, CGP, AQA'
Air resistance; and falling objects, pages 156-7, GCSE Physics, Hodder, AQA'