Simple MachinesSimple Machines

Chap 12-2Chap 12-2

6 Simple machines6 Simple machines2 families Levers and Incline 2 families Levers and Incline

PlanePlane1- Lever (3 classes)1- Lever (3 classes)2- Pulley2- Pulley3- Wheel and Axel3- Wheel and Axel4- Incline plane 4- Incline plane

6 Simple machines6 Simple machines5- Wedge5- Wedge6- Screw6- ScrewDefinition- Basic form of Definition- Basic form of

machine that can be machine that can be combined to form a combined to form a compound machinecompound machine

LeversLeversAll levers have a ridged bar All levers have a ridged bar

that is free to move about that is free to move about the fulcrum (fixed point) the fulcrum (fixed point) when effort is appliedwhen effort is applied

Levers continuedLevers continued 11stst class has effort (e) then class has effort (e) then

fulcrum (f) then the resistance fulcrum (f) then the resistance (r) such as a Tire iron(r) such as a Tire iron

Levers continuedLevers continued 22ndnd class levers has fulcrum (f) class levers has fulcrum (f)

then the resistance (r) then the then the resistance (r) then the effort such as a wheelbarroweffort such as a wheelbarrow

Levers continuedLevers continued 33rdrd class levers has fulcrum (f) class levers has fulcrum (f)

then the effort (e) then the then the effort (e) then the resistance (r) such as a fishing resistance (r) such as a fishing polepole

PulleysPulleysChain, belt or rope wrapped Chain, belt or rope wrapped

around a fixed grooved around a fixed grooved wheel.wheel.

A type of lever where the A type of lever where the middle of pulley acts like middle of pulley acts like the fulcrumthe fulcrum

Pulleys con’tPulleys con’tPulley can increase the Pulley can increase the

mechanical advantage mechanical advantage many time depending on many time depending on how many weight how many weight supporting ropes (figure 6)supporting ropes (figure 6)

Wheel and axleWheel and axle33rdrd type of lever class type of lever class A Lever or pulley (wheel) A Lever or pulley (wheel)

connected to a shaft (axle)connected to a shaft (axle)2 different circular objects 2 different circular objects

with different diameterswith different diameters

Incline plane familyIncline plane familyA slanted surface that A slanted surface that

changes the size and changes the size and direction of the force direction of the force needed. Longer ramp = needed. Longer ramp = less force neededless force needed

WedgeWedgeIs a modified incline plane Is a modified incline plane

or 2 incline plane back to or 2 incline plane back to back such as a ax blade or back such as a ax blade or nails (tips)nails (tips)

Turns 1 downward force Turns 1 downward force into 3 side directed forcesinto 3 side directed forces

ScrewScrewAn incline plane wrapped An incline plane wrapped

around a cylinder.around a cylinder.The gentle sloping threads The gentle sloping threads

requires small force to requires small force to move.move.

Compound MachinesCompound Machines2 or more simple machines 2 or more simple machines

combined together such as combined together such as a bicycle- wheel and axle a bicycle- wheel and axle and levers.and levers.