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Friction. What factors affect friction?. Types of surfaces How hard the surfaces are pushed together. Types of Surfaces. Smoother the surface- smaller the friction Examples of smooth surfaces The rougher the surface- greater the friction Examples. What happens when we change a surface?.
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What factors affect friction? • Types of surfaces • How hard the surfaces are pushed together
Types of Surfaces • Smoother the surface- smaller the friction • Examples of smooth surfaces • The rougher the surface- greater the friction • Examples
What happens when we change a surface? • How does adding rubber to the bottom of an object change the friction? • What happens when the gym floor is dusty? • How are other ways a surface changes the friction?
Types of Friction • Sliding • Two solid surfaces slide over each other • Direction of motion is OPPOSITE that of friction • Examples: • Static • Objects that aren’t moving • Think about trying to push something that just won’t move • examples
Types… cont’d • Rolling • When an object rolls across a surface • Easier to overcome than sliding friction • Think about pushing a bike, is it easier or harder if the wheels are locked? • Fluid • When a solid object moves through a fluid • Easier to overcome than sliding (think about an icy sidewalk )
How hard the surfaces are pushed together……… • What does this really mean? • What are real world examples of pushing surfaces together to increase friction?