simple machines simple machines. machine vs. simple machine machine: any device that makes work...
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Simple MachinesSimple Machines
Machine vs. Simple Machine vs. Simple MachineMachineMachine: Any device that makes
work easierSimple Machine
◦A device that does work with only one movement.
◦There are four main simple machines
Advantages of Simple Advantages of Simple MachinesMachinesMakes work easier by changing
the force you exert in size, direction or both.
Help overcome gravity and friction
2 Kinds of Work2 Kinds of WorkWork done by the machine (Wout)
Work done on the machine (Win)
Wout is always smaller than Win due to friction
W= f X d (J)
Applying ForceApplying Force2 forces when a machine does
work:◦Effort Force (Fe): the force applied to
the machine◦Resistance Force (Fr): the force
applied by the machine
Mechanical AdvantageMechanical AdvantageThe number of times a machine
multiplies the effort force MA = resistance force = Fr
effort force Fe
The higher the MA the lower the effort put in
Inclined PlaneInclined PlaneFlat slanting surfaceConnects one level to another
Modified Inclined Planes: Modified Inclined Planes: ScrewScrew
Screw◦Inclined Plane wound around a rod
Modified Inclined Planes: Modified Inclined Planes: WedgeWedge
WedgeInclined plane that movesInclined Plane that cuts
Inclined Plane MA Inclined Plane MA FormulasFormulas
Ideal Mechanical Advantage
IMA= de (length of slope)
dr (height of slope)
D=distanceE= effortR=resistance
Actual Mechanical Advantage
AMA= Fr (mass)
Fe (effort)
F=forceE=effortR=resistance
LeverLever
Pivots around a fulcrum which can increase force or increase distance
Effort armResistance arm
Mechanical Advantage of Mechanical Advantage of LeversLeversIMA = length of effort arm =
Le length of resistance arm Lr
AMA= R E
Classes of LeversClasses of Levers
First Class (EFR)◦ Ex: seesaw
Second Class (FRE)◦ Ex: Wheelbarrow
Third Class (REF)◦ Tweezers
Effort Resistance
Fulcrum
PulleyPulleyRope passing over a
grooved wheelChanges direction of
force or amount of force
PulleyPulley
Can be movable or fixed
Block and Tackle: combinations of pulleys to gain a large MA
AMA= R (resistance E (effort)IMA= Number of supporting strings
Wheel and AxleWheel and Axle
Wheel rotating around an axle
Ex: Doorknobs, faucets, etc.
Mechanical AdvantageMechanical Advantage
MA FormulaMA Formula
AMA= R
E
R=ResistanceE=Effort
IMA= Rw Ra
R=Radiusw=wheela= axle