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Friction and pressure. Physics. Frictional force. Friction acts on materials that are in contact with one another Friction is caused by irregularities in the two surfaces meter stick demo. friction. The force of friction depends on:. Kinds of material
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Friction and pressure Physics
Frictional force • Friction acts on materials that are in contact with one another • Friction is caused by irregularities in the two surfaces • meter stick demo
The force of friction depends on: • Kinds of material • how much the surfaces are pressed together • Friction does not depend on the amount of surface area in contact • friction turns mechanical energy into heat • heat demo(fire drill)
Friction occurs in liquid and gas • Liquids and gas are called fluids (because they flow) • air resistance is a common form of fluid friction
Is it possible to move at a constant velocity: • Even when a force is applied? • terminal velocity ( no acceleration)
A free body diagram: • Shows all the forces acting on an object
Pressure • Pressure = force / area • The bigger the area the less force • Smaller the area the more force • ice skater • knife blade
Atmospheric pressure • Atmospheric pressure is 10.13 N/cm2 • Egg in the bottle demo • Shrink wrap demo