Friction is Always There to Slow Things Down Flashcards
Why will an object always slow down if it has no force propelling it along?
Because of friction
What is friction?
A force that opposes motion
What needs to happen to travel at a steady speed?
Things always need a driving force to counteract the friction
What are the 3 ways in which friction occurs?
- between solid surfaces which are gripping
- between solid surfaces sliding past each other
- resistance or ‘drag’ from fluids
What is the friction between solid surfaces which are gripping also known as?
Static friction
How can you reduce the friction between solid surfaces sliding past each other?
By putting a lubricant like oil or grease between the surfaces
What can friction between solids often cause?
Wear of the two surfaces in contact
What is the most important factor in reducing drag in fluids?
Keeping the shape of the needy streamlined, like sports cars or boat hulls
Why do lorries and caravans have ‘deflectors ‘ on them?
To make them more streamlined and reduce drag
What do roof boxes on cars do?
Spoil their streamlined shape so slow them down
For a given thrust, the higher the drag…
The lower the top speed of the car
What is the opposite extreme to a sports car?
A parachute which is about as high drag as you can get - the whole point
In a fluid, friction always increases as…
The speed decreases
