Conservation of energy GapFill

In any process, energy is conserved, meaning that energy  can be destroyed but cannot be createdcannot be created or destroyedcan be created but cannot be destroyedcan be created and destroyed. However, energy can be transferred between stores; for instance, when a ball is thrown straight up, its kinetic energy is converted into  stasisgravitational potential energyweightgravity, or when boiling a kettle, electrical energy is transferred to the  non-electrical energymotiontemperaturekinetic energy of the water particles.

If energy is transferred irreversibly in a way that we don't consider useful (often to thermal energy lost to the environment), we say that this energy has  been lostbeen destroyeddissipatedbeen used up. An example of this could be that when a stone is thrown against a rigid wall and it ‘bounces back’, some energy is transferred as  wasted energysound and heatinefficiencyan imprint on the wall. If a heated building is losing a lot of thermal energy to its surroundings, the walls can be  distributedlubricatedinsulatedheated more.

The modern world depends on energy resources for a variety of applications, including electricity generation, transport and heating. Energy resources are categorised as either  good or badnew or oldreplenishable or non-replenishablerenewable or non-renewable, based on whether or not there is a finite amount of a resource or whether more of the resource is produced continuously.

Some energy resources, such as  fossil fuelswind powersolar powernuclear power, give off a lot of by-products, and can contribute to pollution and climate change. Others don't have these same by-products, but might have other drawbacks, such as  being difficult to minebeing dependent on weather or locationthe type of electricity they generatetheir environmental impact. The amount of power generated in the UK from renewable sources has  more than doubleddecreasedstayed the sameincreased a small amount between 2014 and 2021.