What is a simple machine & why have them? · 2014-11-10 · Types of Levers There are three types...
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What is a simple machine & why have them?
Transcript of What is a simple machine & why have them? · 2014-11-10 · Types of Levers There are three types...
Simple Machines
Friction Review
Friction is the force we feel when things rub
against each other
The more things are pushed together, the
more friction there is
It is the force that opposes motion.
Friction Review Friction slows down the movement of things
and turns motion into thermal energy
(heat).
When you rub your hands together you can
feel the thermal energy produced.
The mucus from a slug will decrease friction
as the slug slides along the ground.
Simple Machines
The purpose of a simple machine is to
A. increase the speed of work
B. change direction the force is acting in
C. increase Mechanical Advantage
- a machine’s ability to multiply input
force
Inclined Plane
A flat surface placed at
an angle to a
horizontal surface:
Examples:
Ramp, roadways, slide,
stairs
Lever
A lever is a rigid bar that rocks back and forth at the fulcrum
When a force is applied at one end, the other end moves.
The object to be moved is the load
Types of Levers There are three types of levers:
1st class lever- fulcrum is between the force and
the load: crowbar, seesaw, pliers
2nd class lever – load is between the
force and the fulcrum: nutcracker
3rd class lever – load and
fulcrum are at either end: broom,
baseball bat, hammer
Wedge
A wedge is made of 2 inclined planes put together
A force is applied to the wedge to drive it into an object
Examples:
knife, chisel, nail, axe
Pulley A pulley is a wheel with a grooved rim for
placement of a rope.
A downward force on one side
results in an upward movement
on the other side.
Examples:
flagpole, curtain cord, mini-blinds
Two Types of Pulleys
1. a fixed pulley –
attached to an object
2. a moveable pulley –
moves with the object
Screw
A screw is a spiral inclined plane.
Examples:
jar lid, machine screw, mountain
road
Wheel and Axle
A bunch of levers pivoting around
one fulcrum.
A wheel or crank
attached to an axle.
Examples:
door knob, wheels of vehicles,
gears
Compound (Complex) Machines
A complex machine is made of two or more
simple machines.
Examples:
Bicycle, wheel barrow, Rube Goldberg
machine
List the simple
machines in the
Rube Goldberg
complex machine
that are numbered.
