chapter 12 lesson 2: simple machines. types of simple machines aa simple machine is a machine that...
TRANSCRIPT
Chapter 12
Lesson 2: Simple Machines
Types of Simple MachinesA simple machine is a
machine that does work with only one movement of the machine.
There are six types of simple machines: lever, pulley, wheel and axle, inclined plane, screw and wedge.
LeverLever
a bar that is free to pivot about a fixed point, or fulcrum
“Give me a place to stand and I will move the Earth.”– Archimedes
Engraving from Mechanics Magazine, London, 1824
Effort arm
Resistancearm
Fulcrum
LeverFirst Class Lever
can increase force, distance, or neither
changes direction of force
r
e
LL
IMA
LeverSecond Class Lever
always increases force
r
e
LL
IMA
LeverThird Class Levers
always increases distance
PulleyPulley
grooved wheel with a rope or chain running along the groove
a “flexible first-class lever”
F
F
E
L
Wheel and AxleWheel and Axle
two wheels of different sizes that rotate together
a pair of “rotatinglevers”
Wheel
Axle
Wheel and Axle input force is applied to the
wheel, output force exerted by the axle.
Ex: Doorknobs, screwdrivers, faucet handles
Inclined Plane Inclined Plane
Slanted surface used to raise objects
hl
ScrewScrew
inclined plane wrapped in a spiral around a cylinder
WedgeWedge
a moving inclined plane with 1 or 2 sloping sides
WedgeZipper
2 lower wedges push teeth together1 upper wedge pushes teeth apart
Ideal Mechanical Advantage (IMA) frictionless machineMA greater than 1 increases force MA = output force = input distance
input force output distance