SIMPLE MACHINES
THE LEVER FAMILY
simple machines One of six basic types of machines which are
basis for all other forms of machines.have a rigid arm and a fulcrum.
six types divided into two families.lever family: inclined plane family:
simple lever (3 types)
simple inclined plane
pulley wedge
wheel and axle screw
FIRST CLASS LEVERS
fulcrum located between points of application of input and output forces.
seesaw
SECOND CLASS LEVERS
• fulcrum is at one end of arm and input force is applied to other end.
• wheelbarrow
THIRD CLASS LEVERS
• multiply distance rather than force. • have a mechanical advantage of less than 1.• arm
PULLEYS
modified levers.point in middle of a pulley is like
fulcrum of a lever.single, fixed pulley has a m. a. of 1.block and tackle: Multiple pulleys working together
PULLEYS
WHEEL & AXLE
a lever or pulley connected to a shaft.steering wheel of a car, screwdrivers, and
cranks
THE INCLINED PLANE FAMILY
multiply and redirect force.turns small input force into large
output force by spreading work out over a large distance.
SIMPLE INCLINED PLANE
Changes both magnitude & direction of force
WEDGE
Functions as two inclined planes back to back.
Turns single downward force into two forces directed out to sides.
SCREW
an inclined plane wrapped around a cylinder.
COMPOUND MACHINES
machine made of more than one simple machine
Examples :scissors • two first class levers joined
at a common fulcrum
car jack • combination of lever with a
large screw
Chapter 12
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