© G.Gilmartin for Intel Teach to the Future, April 2001 Simple Machines It’s amazing the workings of a wheelbarrow

© G.Gilmartin for Intel Teach to the Future, April 2001 What is a Machine? A machine is a device that uses energy to help us do work more easily. Machines increase force, change the direction of force, and increase the rate of work. Unhappily, machines do not decrease the amount of work to be done.

© G.Gilmartin for Intel Teach to the Future, April 2001 What does it do? A Simple Machine helps us to make better use of our muscle power in order to do work. Compound Machines are made up of two or more simple machines.

© G.Gilmartin for Intel Teach to the Future, April 2001 Where did they come From? Human beings suffer from an insatiable desire to create labour-saving devices. Throughout history, people have learned ways and devised machines to make work easier. Prehistoric Man probably used tree branches as levers to move large stones. They used sharpened stones (wedge) as cutting tools (e.g.Spear,axe and scraper)

© G.Gilmartin for Intel Teach to the Future, April 2001 The History continues The Egyptians used logs as rollers (wheel) to move huge stone blocks up large slopes (inclined plane) when they built the pyramids. Sadly for the Egyptian Slaves, the pulley wasn’t discovered until much later. Greek & Roman civilizations are known to have used the developments of the pulley and the screw.

© G.Gilmartin for Intel Teach to the Future, April 2001 The Lever This is a rigid bar, free to rotate about a fixed point called the fulcrum or pivot. There are three types of lever which are classed depending on the position of the Fulcrum, Load and Effort. 1. First Class Lever; This is like a see-saw. The fulcrum is between the load and the effort. 2. Second Class Lever; This is like a wheelbarrow. The load is between the fulcrum and the effort. 3. Third Class Lever; This is like a tweezers. The effort is between the load and the fulcrum.

© G.Gilmartin for Intel Teach to the Future, April 2001 The Inclined Plane This is simply a straight, sloping surface, or ramp, which is used to lift heavy loads with relatively little effort. Examples include; Wheelchair access ramps, Stairs, Ships gangplank for boarding passengers, etc.

© G.Gilmartin for Intel Teach to the Future, April 2001 The Wheel and Axle This is basically a solid disc or circular frame,(Wheel), mounted on a round bar,(Axle). The wheel developed from the roller as a means of moving heavy loads and is made to revolve on a central axis, the axle. The Wheel and Axle is a form of modified lever, where the center of the axle acts as the fulcrum.

© G.Gilmartin for Intel Teach to the Future, April 2001 The Pulley This is basically a grooved wheel which is mounted on a solid axle. A rope, belt or chain passes over the wheel, fitting into the groove so as not to slip off. A simple pulley changes the direction of motion, i.e. pulling down on one end of the rope raises a load fixed to the other end over the pulley.

© G.Gilmartin for Intel Teach to the Future, April 2001 The Wedge This is a form of inclined plane which is free to move and is used to increase force. A wedge consists of either one or two sloping surfaces which can be used to cut (knife), split (axe) or fasten (nail) materials. All cutting tools have a wedge shape.

© G.Gilmartin for Intel Teach to the Future, April 2001 The Screw This is basically an inclined plane which is wrapped around a cylinder forming a helix. Screws have many different functions; e.g. Screws, nuts and bolts for fastening materials, Screw jack for lifting heavy weights, Augers for drilling and Propellers for driving boats and planes.

© G.Gilmartin for Intel Teach to the Future, April 2001 Related Terms Energy is the ability to do work. A person usually provides the energy to operate a simple machine. Work is done when you apply a force to move an object. Work(Nm)=Force(N) x Distance(m) The work done is always less than the effort put in because of friction in the machine. Force is the push or pull which causes an object to move or change shape. A person uses force, for example, to move a lever. This applied force is called the effort while the resisting force is called the load. Rate of work is the speed of doing work. This is called Power. Power(watts)=Work(Nm) x Time(s)