P4 - Forces Flashcards
Describe qualities of friction…
Friction occurs as a result of an applied force.
This resists the movement of an object.
Friction increases with the applied force to a limit and after this point the friction is them less than the other force, meaning that the object can move.
Describe the friction between solid surfaces…
This involves the friction between shoes and the ground.
This allows you to push against the frictional force, giving you forwards momentum.
Describe the friction forces between sliding solid surfaces…
This occurs with parts in car engines. This can be reduced with a lubricant like oil or grease.
Describe drag from fluids…
This is the resistance from molecules in a fluid, such as air or water.
To overcome the resistance the vehicles need to push past all the molecules meaning that a big squarish car will have more resistance than a streamlined car.
Why is there no resistance in space?
This is a vacuum and there is no fluid.
Describe how an interaction pair works?
If you push against a wall the wall pushes back in an opposite direction with the same force. Once pushing has stopped the wall stops pushing in return. There must be an opposite force as otherwise the wall will fall over.
Why can forces in an interaction pair cause movement ?
The forces act on different objects. In a jet engine, air is used to burn fuels, producing exhaust gases. The engine exerts a force on the exhaust gases, making them accelerate backwards. The exhaust gases exert an equal but opposite force on the jet to give it forward momentum, causing it to move forwards.
