Download Friction PPT

Friction
Friction
 The force that two surfaces exert on each
other when they RUB against each other
Factors
 The strength of the friction depends on 2
factors
 How hard the surfaces push together
 Rubbing hands together
 Types of surfaces involved
 Rough vs smooth?
More about friction
 Friction acts a force in the opposite
direction as the moving force (opposite
directions you subtract)
 With out friction an object in motion
would not stop until another object hits it
Types of friction
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Static
Sliding
Rolling
Fluid
Static friction
 Makes you exert extra force to get an
object that is sitting still to start moving
 It acts as an opposite force
Sliding friction
 ONCE the object is moving this is the
friction between the two objects is sliding
friction
 Can be useful to make surfaces less slick
 Can be hurtful, cause you to slow down,
cause things to be destroyed or tear up
(skin sliding across blacktop)
Rolling friction
 When an object rolls across or over
another surface
 Easier to overcome than sliding friction
for similar objects
Fluid friction
 When a solid object moves (pushes) a
liquid aside
 Easier to overcome than sliding friction
 This is why parts in machines are covered in
oil or grease