Work and simple machines

Turn and Talk

What does work mean?

Work is: Effort exerted over

a certain distance.

What Is Work?

Work is the transfer of energy to an
object.
In science, work is done when a force
causes an object to move in the
direction of the force.

How to Calculate Work

We use the equation W = F x D “Work equals Force times Distance”

SI (International System)

Units of Measurement

We measure work in J.

J stands for Joule

A Joule is a Newton times a

meter.

Joule = N x m

What is a Machine?

A machine is a
device that
makes work
easier by
changing the
size or direction
of the force.

Work Input and Work Output

When you use a machine,
you do the work on the
machine and the machine
does the work on
something else.

The work that you do on the
machine is called the “work
input”.
The work done by the
machine is called the “work
output”

The “work output” can
never be more than the
“work input”

Machines Can Change The Input Force

Machines Change the Size or

Distance of an Input Force

Mechanical Advantage

Some machines
increase force more
than other machines
can.
The amount of
times that a
machine multiplies
the force is called
mechanical
advantage.

Mechanical Efficiency

Mechanical
efficiency is the
comparison of a
machine’s work
output with the
work input.

We measure it with
the following
equation:

Simple Machines

There are six basic simple machines that
help make our lives much easier.

Inclined Plane

An inclined plane
is a simple
machine with a
straight slanted
surface. A ramp
is an inclined
plane.

Lever

A lever is a simple machine that has a bar that
pivots about a fixed point called a fulcrum.

There are 3 types of levers:
1st Class 2nd Class 3rd Class

Pulley

A pulley is a
simple
machine
that has a
grooved
wheel that
holds a rope
or cable.

Wheel and Axle

A wheel and axle is a simple machine that
consists of two circular objects of different
sizes.

Screw

The simple machine called
a screw is an inclined
plane wrapped in a spiral
around a cylinder.

Wedge

The simple machine
called a wedge is a pair
of inclined planes that
move.

Compound Machines

Compound machines are
machines that are made
up of two or more simple
machines.

Work/Power Video