6.3 – Simple 6.3 – Simple MachinesMachines
ObjectivesObjectives
Describe and identify examples of the six types of simple machines.
Explain how the different types of simple machines make work easier.
Simple MachinesSimple Machines
A machine that does work with only A machine that does work with only one movementone movement
Two FamiliesTwo Families Levers – levers, pulleys, & wheel and Levers – levers, pulleys, & wheel and
axleaxle Inclined Planes – inclined plane, screw, Inclined Planes – inclined plane, screw,
& wedge& wedge
LeverLever
Bar that is free to pivot about a fixed Bar that is free to pivot about a fixed pointpoint Fixed point = fulcrumFixed point = fulcrum
Input arm is part on which input Input arm is part on which input force is appliedforce is applied
Output arm is part that exerts the Output arm is part that exerts the output forceoutput force
First-class LeversFirst-class Levers Fulcrum is located between input Fulcrum is located between input
and output forcesand output forces Multiplies and changes direction of Multiplies and changes direction of
forceforce
http://www.sciencebyjones.com/Firce_class_lever_drawing.gifhttp://www.cool-science-projects.com/images/man-and-lever.jpg
Second-class LeversSecond-class Levers Output force is located between Output force is located between
input force and fulcruminput force and fulcrum Always multiplies forceAlways multiplies force
http://cache.eb.com/eb/image?id=63039&rendTypeId=4
Third-class LeversThird-class Levers Input force is between output force Input force is between output force
and fulcrumand fulcrum Doesn’t multiply force but does increase Doesn’t multiply force but does increase
distance over which force is applieddistance over which force is applied
33rdrd class lever class lever
FulcrumOutput force- the staple goes through the papers
Input force- your hand squeezes the stapler
Classes of LeversClasses of Levers
First Class LeverFirst Class Lever
Second Class Second Class LeverLever
Third Class Third Class LeverLever
Lever & Ideal MALever & Ideal MA
Calculating ideal mechanical Calculating ideal mechanical advantage (IMA) of a lever:advantage (IMA) of a lever: IMA = length of input arm divided by IMA = length of input arm divided by
length of output armlength of output arm
PulleyPulley
A grooved wheel with a rope, simple A grooved wheel with a rope, simple chain, or cable running along a groovechain, or cable running along a groove Modified first-class leverModified first-class lever The point in the middle of the wheel is the The point in the middle of the wheel is the
fulcrumfulcrum The rest of a wheel acts like the rigid arm.The rest of a wheel acts like the rigid arm.
Three types: fixed, moveable, block &tackleThree types: fixed, moveable, block &tackle
http://www.technologystudent.com/gears1/pulley7.htm
Types of PulleysTypes of Pulleys
Fixed = attached Fixed = attached to something and to something and doesn’t movedoesn’t move
Force is not Force is not multiplied but multiplied but direction is direction is changedchanged
IMA = 1IMA = 1
Types of PulleysTypes of Pulleys
Movable = has one end of the rope Movable = has one end of the rope fixed and the wheel free to movefixed and the wheel free to move
Multiples forceMultiples force IMA = 2IMA = 2
Types of PulleysTypes of Pulleys
Block & Tackle = Block & Tackle = system of pulleys system of pulleys consisting of fixed and consisting of fixed and movable pulleysmovable pulleys
IMA = number of ropes IMA = number of ropes supporting the weightsupporting the weight
Block and TackleBlock and Tackle
Pulley websitePulley website
Lever and Pulley Video ClipLever and Pulley Video Clip
Wheel & AxleWheel & Axle
Machine with Machine with two wheels of two wheels of different sizes different sizes rotating rotating togethertogether
Modified leverModified lever
Wheel & AxleWheel & Axle
IMA = radius of IMA = radius of wheel divided by wheel divided by radius of axleradius of axle
Gears are modified Gears are modified formsforms
Inclined PlaneInclined Plane
Sloping surface that reduces the Sloping surface that reduces the amount of force required to do workamount of force required to do work
Inclined PlaneInclined Plane
IMA = length of slope (input IMA = length of slope (input distance) divided by height of slope distance) divided by height of slope (output distance)(output distance)
Less force is required if ramp is Less force is required if ramp is longer and less steeplonger and less steep
ScrewScrew
Inclined plane wrapped in a spiral Inclined plane wrapped in a spiral around a cylindrical postaround a cylindrical post
IMA = Length of Handle divide by length IMA = Length of Handle divide by length of Shaftof Shaft
WedgeWedge
Inclined plane with one or two Inclined plane with one or two sloping sidessloping sides
http://kmoddl.library.cornell.edu/stillImages/Clark/small/003.jpg
Compound MachineCompound Machine
Uses a combination of two or more Uses a combination of two or more simple machinessimple machines
Cool LinksCool Links
Simple MachinesSimple Machines
In-Class In-Class Assignment/HomeworkAssignment/Homework
6.3 Reinforcement WKT6.3 Reinforcement WKT