WorkWork happens when a force moves an

object over a distance.The formula for work is:

W = F X D

If the object does not move, NO work is done! (Scientifically speaking)

How much work is done depends upon:

The amount of force (f) exerted. The distance (d) over which the force is

applied.

PowerPower is a measure of the rate of doing

work.

Power = work/time or F x D

T

Simple Machines A simple machine is a machine with only

one movement. They are the simplest

form of tools. A simple machine has

few or no moving parts.

6 Types of Simple Machines Inclined PlaneLeverPulley (modified lever)Wheel and Axle (modified lever)Wedge (modified inclined plane)Screw (modified inclined plane)

All simple machines change the way work is done.

They do not make less work. The work done by using the simple

machine to do a job will be at least equal to the work done if the machine had not been used, and likely will be more because of friction.

Work = force x distanceA machine can make work easier

(requiring less force) or faster (reducing the distance).

When the distance is increased, the force is decreased, and visa versa, but the work does not change.

Mechanical AdvantageThe number of times a machine

multiplies the force (effort) applied.How much easier and faster a machine

makes your work.

Under ideal conditions (no friction), the work put into a machine will equal the work coming out, or:

work input = work output

Fi x Di = Fo x Do

Work In = Work Out

Work Input (Wi) = The amount of work YOU put into moving an object.

Work Output (Wo) = The amount of work you actually GET from moving the object.

Work input = Work outputFi x Di = Fo x Do

Force Input (Fi) = Effort you put into moving the resistance of load.

Distance Input (Di) =The distance YOU move when using a simple machine.

Force Output (Fo) = Resistance or load that is moved.

Distance Output (Do) = The distance the resistance or LOAD moves when you apply a force.

Efficiency (E)The efficiency of a machine tells us how

much of the work going into the machine is used to produce work going out and how much is lost to friction.

Work output = Work input - Friction85% efficiency means that 15% of your

input work is wasted or lost to friction.

Compound Machines Simple Machines

can be put together in different ways to make complex machinery.

Compound machine - made up of two or more simple machines.