KEY IDEAS

• Machines transfer energy from a source to where it is needed
• Gears, belts, chains and cogs can all transfer energy and change the direction of movement

EXAMPLE QUESTIONS

• Where do different forms of energy to make machines work come from?
• How do different machines get their energy?
• What different ways can energy to be transferred in machines?

RAMPS AND PULLEYS MAKE JOBS EASIER

• A ramp provides a way of moving a load upwards that requires less effort than lifting.
• The ramp was one of the earliest means of making jobs easier and as the main method of moving stones in the building of Egyptian pyramids.
• Many machines have systems designed to transfer energy from one part to another via pulleys and gears.
• Both pulleys and gears can reduce the effort needed to move a large load.
• Everyday examples include bicycles and mechanical clocks.

LEVERS MAKE TASKS EASIER

• We make great use of levers in our everyday lives.
• In fact, levers represent one of the earliest form of tools and are still widely used today in one form or another.
• A see-saw, a row boat and a nutcracker all incorporate levers.

GEARS AND COGWHEELS CAN CHANGE THE SPPED AND DIRECTION OF MOTION

• Windmills work because of the ability of gears and cogwheels to transfer motion from one part of the apparatus to another.
• Gears and cogwheels convert the movement of the vertical sails to the horizontal movement of the grinding stones.
• Gears can also change the speed of motion.
• A small cogwheel, linked to a cogwheel with twice as many teeth, will result in the larger cogwheel taking twice as long to complete one revolution.
• Bicycles and motorcar gears are familiar modern day examples of this.