Conservation of energy

• The total kinetic energy is the sum of all individual objects' kinetic energies.
• Most people would say that a car has a lot of energy because it's moving, but where is the energy when the car has stopped?
• The energy in a car is stored in the petrol, which needs oxygen from the air to burn.
• The energy is stored whilst the petrol and oxygen are kept apart in a chemical store.
• Energy has to be transferred using energy carriers, mechanically for example, kicking a football, electrically for example when using electricity at home, or by radiation for example light and microwaves.
• When cooking using a camping gas stove, the energy stored in the butane and oxygen system is transferred by heating to a thermal stall in the pan of water.
• Some heat is wasted when cooking using a camping gas stove, hence it is more efficient to use a battery-powered drill.
• The chemical store of energy in a battery-powered drill is transferred electrically to the motor which transfers it mechanically by the movement of the drill to a thermal stall.
• As the drill and the wall get hot, some energy is also transferred by sound waves which also heats up the brain and environment as the sound vibrations are absorbed.
• Energy is conserved, meaning it is constant in any change, but some always gets wasted.