Simple Machines

By: Lee Despres

The Lever

A Lever is a bar that rotates at a fixed point called a fulcrum.There are three different types of levers Class 1, 2, and 3. The way they differ is where the fulcrum is located.The way it works is when you apply a force or an input force to one side that is small and is spread out over a long distance and the lever applies a greater force over a smaller distance.

Lever continued

We do the same amount of work but we do less work over a longer distance and the lever applies a greater force over a shorter distance (the mechanical advantage)the force distance trade of is we apply a force that is less than the output force but the load doesn't move as high. To find the macanical advantage you do Distance 1 (input force to fulcrum) divided by distance 2 (fulcrum to load)

Pulley

A pully has a grooved wheel that holds a rope or cable.There are three types of levers, Fixed,Movable, and block and tackle.The way these are different is fixed is stuck to a pole,movable moves with the load, and Block and Tackle is a series of pulleys.The way it makes work easier is you apply a small force over a small distance and the rope applies a big force over a small distance.But the load doesn't go as high.Force distance trade off.

Pulley Continued

To Find the MA you need to know what pulley you are using. A fixed pulley's MA is one.Movable pulley's MA is two. The block and tackle's MA is how many segmants of rope there is.
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Wheel and axle

A Wheel and axle is a big wheel that turns a smaller cylinder. The way it works is you apply a force to the wheel and it applies the force to the axle but since it is smaller it spins the axle faster.The MA is found by dividing the diameter of the wheel by the diameter of the axle.The force distance trade off is you apply a smaller force over a longer distance

incline plane

An incline plain is basically a ramp. The way it works is you apply a smaller force but you apply that force over a long distance.That is the force distance trade off too,low force but over a longer distance.The way you find the MA is you divide the lenth of the ramp by the hight of the ramp.

Screw

A screw has an inclined plane wrapped around a cylinder.The way it works is it lets you apply a smaller force but over a longer distance which is the force distance trade off. (what a surprise) and it applies a greater force over a shorter distance so it can penetrate the wood.

Wedge

A wedge is just to incline planes put together. Wedges make work easier by letting you apply a smaller force over a longer distance and the wedge apples a large force over a shorter distance.That is why it splits wood easily. That is also the force distance trade off less work over a longer distance.To find the MA you divide the length of the wedge by how thick it is.

Compound Machine

A compound machine is made up of two or more simple machines. Most machines you see around you are compound machines. They make work very easy, even easier then simple machines.To find the ME of a compound machine you divide the output work by the input work.