Energy and Simple Machines

Energy is needed to do work.
Work is the transfer of energy to an object by applying force.
Machines transfer energy more efficiently and can lessen the amount of work.
Conversion of energy is the process of changing energy from one form to another.

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Energy

It is the sum of potential energy (stored energy) and kinetic energy (energy of motion).

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Mechanical Energy

Sound energy is carried by air vibrations.
When these vibrations enter a microphone, it moves a diaphragm, which is converted into electrical signals.

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Conversion of Sound Energy

Engines can convert heat into mechanical energy.
An internal combustion engine takes advantage of the burning of gasoline which contracts and expands air that moves mechanical parts.

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Conversion of Heat Energy

Electrical energy is generated by the movement of electrons along a circuit.
When electrons encounter resistance (like a lightbulb) they slow down and generate heat and light.

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Conversion of Electric Energy

Light is the visible part of the electromagnetic spectrum - energy radiated from the sun.
Light is converted into other forms of energy by plants through photosynthesis.

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Conversion of Light Energy

Machines can magnify or redirect force to accomplish work.
Complex machines are just combinations of these six simple machines. They help us accomplish work with less time and energy.
The six simple machines are inclined plane, wedge, screw, wheel and axle, and lever.

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Simple Machines

It is a flat surface tilted at an angle.
Examples are ramps, ladders, slides, fly-overs, slopes, etc.

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Inclined Plane

It is a sharpened tool. Wedges are actually two inclined planes.
Examples are blades like knives, saws, nails, screwdrivers, etc.

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​Wedge

A screw is an inclined plane wrapped in a cylindrical shape. Its edges are called "threads".
Examples of screws are screw pumps, jar lids, drills, bottle caps, faucets, car jacks, etc.

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Screw

The axle is a bar where the wheel spins on. Land vehicles will not function without wheels.
Examples are bicycle and car tyres, ferris wheel, electric fans, clocks, pizza cutters, doorknobs, mills, etc.

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Wheel and Axle

A pulley is a wheel turned by pulling a rope, cord or chain.
Fixed pulley - does not move with the object being pulled.
Movable pulley - moves with the object from one side to the other.
Block and tackle pulley - multiple pulleys used to carry heavy loads.

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Pulleys

A lever is a beam or rod that moves up or down on a fulcrum. The force is applied on one part of the beam or rod and it moves a load on the other side.

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Lever

First-class levers have the fulcrum between the applied force and the load.

First class lever

Second-class levers have the load between the fulcrum and the applied force.

Second class lever

​Third-class levers have the applied force between the fulcrum and the load.

Third class lever