Simple Machines
Work and Power Lab
• So last time we saw that the amount of
work you do depends on a force being
used to move an object a certain distance.
faster
accomplish it, the more
So, The
if someone
has toyou
get themselves
It doesn’t matter how fast you do it, as long as the force and
up a certain distance, then they have to
the distance
remainis!
the same, the work is the same as well!
power
there
do
the equivalent
amount of work
The effort Homer needs to
jump up is the force!
The height of
this staircase
is the distance
The force of the jump x height of the stairs is the work homer accomplished!
They
can
just
pick
it
up
Or,
they
could
use
a
machine
of
IfHow
someone
to
liftthe
a
does
itneeded
apply
to
There
are
two ways
to do
it real
but
themselves
and
lift
it;
but
this
some
kind
that
will
do
the
same
amount
of
work
isof
still
the
same!
box
to
the
top
the
pile…
life?
couldbut
take
lots
of effort!
work
with
less
effort!
?
What is a machine?
• A machine is a device that usually makes
work easier
• Main Concept 3: Simple Machines makes
work easier by changing two factors:
Force & Distance.
– Remember: Work = Force x Distance
Force
You will be seeing how each
simple machine manipulates
force and distance.
Distance
6 Different Types of Machines
Homer could choose from:
Wheel
& Axle
Input and Output
Machines involve two forces to accomplish work. Main Concept 4:
As a result of the Input force, an Output force occurs
and work gets done on an object!
Input Force (Effort Side)
Output Force (Result Side)
• Push or pull that you
have to do to the
machine
•Push or pull the machine
does on the object
• Example: Pushing keys
on a keyboard
•Example: What appears
on a computer screen
• Person moves a shovel
•Shovel moves the dirt
• Look for green to show
the input in this slide
show
•Look for yellow to show
the output in this
slide show
Lever
Input work (Effort Side)
Output work (Result Side)
Force
Force
Basically, this is a board that is placed on a pivot point called a fulcrum
As you apply a force to one side
the other side applies a force to the
object you want moved!
Here is the distance
needed
Pulleys
When
you
a pull
to one
side
A pulley
isapply
a wheel
withforce
a rope
wrapped
of the rope,
rope applies
a pull
around
it andthe
attached
to the object
force
towant
the object
side
you
to move.
and the object gets lifted
Output (work side)
Force
Which side of the pulley is the
input and which is the output?
Think: has the distance
required changed?
Incline Plane
An incline plane is a ramp that increases the distance needed to
move an object but makes the work easier to do.
Where is the input and
output sides?
Output work (Result Side)
Homer may have to push the box up,
but it takes less effort than simply lifting it
Think: has the distance
required changed?
The work has been spread out over a greater distance than lifting straight up!
Therefore it is easier to accomplish (takes less effort)!
Wedge:
A wedge works like two
ramps put together.
Input Force
Output Force
As the input force pushes down,
the output force pushes out,
splitting the object
The input
and
output
of
a
wheel
The Wheel & Axle
and axel
will all depend on how you use it.
If it is used as
If
it is used
as to
a
steering
wheel
wheel
tosomething
move a car
turn (or
(or something
like it) like it)
Then the
the Input
input
Then
comes through
through the
the
comes
axel
and and
the output
wheel
the
is output
from the
turning
is from
of the
the axel
wheel
Either
axelHomer
turns the
or
Q: Howthe
could
usewheel
a wheel
the
turns
thebox?
axel.
andwheel
axle to
lift his
Homer turns the crank on the
wheel and the box on the ramp
moves up
Don’t forget!
This is the work Homer
Is trying to do!
= Lift the box this distance
Now you would have to ask when a machine this size
would be worth the effort to make it
Maybe if there were a lot of boxes
to lift = more work to do
The use of a wheel and axle are actually very common
The rear wheel turns more for each time you
pedal causing you to travel farther with less force
Slow
Compound
Machine
Fast
“Compound Machine”
Any combination
oforseveral
simple
A compound
machine is simply two
more simple machines
put
together.
machines…
Notice that there are at least 4 different
simple machines in this one compound machine
Simple machines are most often used
in combinations like this!