Simple Machines SPH4C March 2010

History Archimedes – 3 rd Century BC Heron of Alexandria – AD Galileo Galilei – 1600 AD

What is a machine? Device that allows us to do work with less effort. Work is done when a force moves an object in the direction of that force.

Work Work is the energy transferred to an object. Machines make work easier. W is the work done on the object, F is the magnitude of the force, Δd is the magnitude of the displacement.

Machines Machines are designed to achieve at least one of five main functions: –Change energy from one form into another –Transfer forces –Change the direction of a force –Change the magnitude of a force –Change distance or speed

Simple Machine Families Lever Family –Lever –Pulley –Wheel and axle –Gears Inclined Plane Family –Inclined plane –Wedge –Screw

Lever A lever is a rigid bar that can rotate freely around a fulcrum ( a support around which a lever can rotate). An effort force, F E, is a force applied to one part of a lever to move a load at another part; the load exerts a load force, F L.

Lever Classes First-class –Fulcrum between F E and F L Second-class –F L between F E and fulcrum Third-class –F E between F L and fulcrum

Other Levers

Inclined Planes An inclined plane is a ramp that increases the load than can be moved by an effort force.

Inclined Planes A wedge is a double inclined plane that increases the applied or effort force. A screw is an inclined plane wrapped around a central shaft that increases the applied or effort force.

Compound Machines A machine made of two or more simple machines.