Friction
From Simple English Wikipedia, the free encyclopedia
Friction is a force that tries to stop the movement of two touching things. Friction also makes heat. Two types of friction are static and kinetic. Static friction deals with objects that are not moving. Kinetic deals with objects that are moving. Facts of friction are:
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Friction is caused by imperfections on the surfaces of two materials. These imperfections are called asperities. As these two rough surfaces move against each other they get stuck and prevent motion until broken or slid over. Even the smoothest of materials have these asperities.
Model of asperities
- As the force that is pushing on the object increases, the static friction increases too. However after awhile the force will get bigger until it matches the maximum static friction making the object begin to move. The object will begin to move at the split second the static friction is less than the force pushing on it. After that point kinetic friction will start effecting the object.
- The coefficient of friction is the value between two things and the force putting them together. For example, a person's skates on ice has a low coefficient of friction, but rubber on concrete has a high one.
- Internal friction in a fluid is called viscosity. This is basically how easy it is for the fluid to move or flow. For example honey is more "viscous" than water. A factor that can alter viscosity is temperature.
- Laminar flow is when two layers of fluids flow over each other.
