Energy transformations and energy transfers

• Energy is stored in your muscles ready to be released.
• The energy from your muscles gets you moving.
• Your muscles store chemical energy.
• When your muscles get you moving, you have kinetic energy.
• Running makes you hot, meaning that energy released in your muscles is wasted as thermal (heat) energy, rather than becoming useful kinetic energy.
• Electricity is useful because it brings energy, available at the flick of a switch.
• Electrical energy from a light bulb is transformed into light energy. Every light bulb also produces thermal (heat) energy.
• A moving object has kinetic energy.
• The faster an object moves, the more kinetic energy it has.
• We need to transfer energy to an object to get it moving, and more energy to get it moving faster.
• If you lift an object up, you give it gravitational potential energy.
• The higher an object is above the ground, the more gravitational potential energy it has.
• Fuels such as coal or petrol are stores of chemical energy.
• Batteries are stores of energy.
• Nuclear fuel is a store of nuclear energy.
• Strain energy is the energy stored by an object that has been stretched or squashed in an elastic way.
• When energy is transferred by a force, we say that the force is doing work.
• Energy spreads out from hot objects, so enery can be transferred through heating.
• Energy can be transferred through waves.
• Energy can be transferred through electricity such as an electric current.
• When energy transforms from one form to another, it is called conversion or transformation.
• Chemical energy = Kinetic energy + g.p.e. + thermal energy + light energy + sound energy
• Two forms of energy we want are kinetic and gravitational potential energy.
• Three forms of energy we don't want are heat, light, and sound.
• The principle of energy conservations tells us that energy cannot be created or destroyed. The total amount of energy is constant.
• Energy is expensive and should not be wasted.
• Most energy ends up being wasted as thermal (heat) energy.
• When fuels are burnt, heat is produced. Hot things lose energy to their surroundings, even if they are well insulated.
• Friction is a problem when things are moving. Lubrication can help to reduce friction, as friction generates heat.
• Another common form of wasted energy is sound. Noisy machinery and loud cars are all wasting energy.
• Efficiency = useful energy output/energy input x 100
• Gravitational potential energy = weight x height or mg x height
• Kinetic energy = 1/2 x mass x speed squared