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