Summary Fluid Mechanics - A level AQA PE

The greater the velocity of a body, the greater the drag.
Eg. Fast sports such as cycling
Drag resistance clothing in skiing fitted suits , boots

Lift causes a body to move perpendicular to the direction of travel

- Upward lift forces keep objects in the air for longer so increased horiziontal distance
- Achieved through different air pressures on an object
- Air that travels fast has lower pressure than air that is low
- Air that travels slowly has higher pressure
- This is called the Bernoulli Principle

- When molecules exert less pressure the faster they travel and more pressure the slower they travel

- Lift Force- causes a body to move perpendicular to the direction of travel eg. Projectiles to stay in the air for
longer, increasing horizontal distance
- Angle of Attack - tilt of a projectile relative to air flow

Lift Force Example - Discus



Downforce - example: racing car, cyclist, speed skiers




- Air travelling over top of cyclist will travel a shorter distance than below it
- Air above travels at a slower velocity and a higher pressure
- Creates a downward lift force to create a faster speed and keep the bike on the track