5.3 Simple Machines

6 Types

Lever A bar that is free to pivot about a fixed point (fulcrum) : the fixed point : distance from the fulcrum to where the effort force is applied. : distance from the fulcrum to where the resistance force is applied

3 Classes of Levers

First Class Lever Used to , always changes the of the applied force. Ex. Screwdriver used to pry paint can lid Fulcrum is in the

Second Class Lever Always – does not change direction of force. Ex. Wheelbarrow Resistance is located between the

Third Class Lever Increases the over which the resistance force is applied. (Does not multiply force) Ex. Baseball bat or hockey stick Effort force is

Mechanical Advantage Lever IMA = length of effort arm length of resistance arm Making the effort arm increases the IMA.

Pulley Fixed Pulley: modified first class lever Moveable Pulley: Attached to ceiling or wall Changes Moveable Pulley: Multiplies IMA = Distance you pull is the resistance distance

Pulley (cont.) Block and Tackle System of IMA =

Wheel and Axle Machine with that rotate together (gears) Ex. Door knob IMA = radius of wheel radius of axle Can be increased by making the

Inclined Planes Sloping surface Reduces the IMA = length height *the the ramp the less force required

Screw Inclined plane wrapped around a cylinder. The closer together the threads, the easier to screw into wood

Wedge Inclined plane with one or two sloping sides Changes the

Compound Machine Two or more simple machines used together. Ex. Can opener Car