# Year 9 Energy Learning Objectives

Students should know and be able to apply the following:

• Power is defined as the rate at which energy is transferred or the rate at which work is done.
• Power = energy transferred/time (P = E/t)
• Power = work done/time (P = W/t)
• An energy transfer of 1 joule per second is equal to a power of 1 watt.
• Students should be able to give examples that illustrate the definition of power eg comparing two electric motors that both lift the same weight through the same height but one does it faster than the other.
• A system is an object or group of objects.
• There are changes in the way energy is stored when a system changes.
• Students should be able to describe all the changes involved in the way energy is stored when a system changes, for common situations. For example:

•• an object projected upwards

•• a moving object hitting an obstacle

•• an object accelerated by a constant force

•• a vehicle slowing down

•• bringing water to a boil in an electric kettle.

• Energy can be transferred usefully, stored or dissipated, but cannot be created or destroyed.
• Students should be able to describe with examples where there are energy transfers in a closed system, that there is no net change to the total energy.
• Students should be able to describe, with examples, how in all system changes energy is dissipated, so that it is stored in less useful ways. This energy is often described as being ‘wasted’.
• Students should be able to explain ways of reducing unwanted energy transfers, for example through lubrication and the use of thermal insulation.
• The energy efficiency for any energy transfer can be calculated using the equation: efficiency = useful output energy transfer/total input energy transfer
• Efficiency may also be calculated using the equation: efficiency= useful power output/total power input
• Students may be required to calculate or use efficiency values as a decimal or as a percentage.
• Students should be able to describe ways to increase the efficiency of an intended energy transfer.
• The main energy resources available for use on Earth include: fossil fuels (coal, oil and gas), nuclear fuel, biofuel, wind, hydro-electricity, geothermal, the tides, the Sun and water waves.
• A renewable energy resource is one that is being (or can be) replenished as it is used.
• The uses of energy resources include: transport, electricity generation and heating.
• Students should be able to:
• describe the main energy sources available
• distinguish between energy resources that are renewable and energy resources that are non-renewable
• compare ways that different energy resources are used, the uses to include transport, electricity generation and heating
• understand why some energy resources are more reliable than others
• describe the environmental impact arising from the use of different energy resources
• explain patterns and trends in the use of energy resources.
• Descriptions of how energy resources are used to generate electricity are not required.
• Students should be able to:
• consider the environmental issues that may arise from the use of different energy resources
• show that science has the ability to identify environmental issues arising from the use of energy resources but not always the power to deal with the issues because of political, social, ethical or economic considerations. 