Improving energy efficiency Energy is often wasted due to friction and heat loss. It is possible to improve the efficiency of a device by reducing the amount of friction or energy lost as heat.
Reducing friction An engine without lubrication is inefficient. There is a lot of friction between the parts of the engine. Energy is wasted as heat and sound. Adding oil as a lubricant will improve the efficiency of the engine.
Reducing heat loss A hot water tank that is not insulated is inefficient. A lot of heat energy is lost from the tank to the surrounding air. The efficiency of the tank can be improved by covering it with a lagging jacket. This reduces the amount of heat energy lost.
Fig. 16 Oil lubricates an engine and reduces friction.
Extended Investigation Design and carry out an experiment to investigate how insulation affects the rate of heat loss from a container. Test various materials to see how good they are at insulating heat.
Fig. 17 Insulating a hot water tank saves energy.
Extended Investigation Design, build and test a device
Design, build and test a device that transforms energy from one form to another in order to perform a function. Describe the energy changes that occur and try to improve its efficiency. Example: A solar-powered car. Energy changes: Light energy Electrical energy Motion energy. To improve efficiency: Make sure all parts are securely attached so that no energy is wasted due to friction. Use lightweight materials.
