How Tools Work

The Six Simple Machines  Lever  Inclined Plane  Wedge  Screw  Pulley  Wheel and Axle

Lever  A bar that pivots on a fulcrum — a fixed point  Levers apply force to a load  Three classes, depending on placement of fulcrum, load, and input force

Inclined Plane  A straight, slanted surface  Ex: a ramp  Requires less input force than going straight up  ***does NOT reduce work (W= f x d)

Wedge  Two inclined planes that move  Often used for cutting  You a knife down as it cuts apart  The sharper the wedge, the greater output force for your input force

Screw  An inclined plane wrapped in a spiral around a cylinder  Usually used as fasteners  Smaller force over a longer distance  The small force of you turning pushes the screw along its spiraled threads

Pulley  A grooved wheel that holds a rope or cable  A load is attached to one end of the rope, and the input force is applied to the other end

Wheel and Axle  Two circular objects of different sizes used to create a larger output force  Turn the larger circle around a longer distance as the smaller circle, traveling a shorter distance, creates a larger output force  The larger the wheel, the less force needed to move the load

Compound Machines  A machine made up of two or more simple machines  Most machines in the world, including how your body works, are compound

Mechanical Advantage  How many times a machine multiplies force  Mechanical Advantage is calculated by dividing the output force by the input force  MA= out/in  If MA > 1, the machine helps lift heavy objects  If MA < 1, the machine increases the distance and reduces the output force

Name that Machine!