Chapter 6: Energy stores and transfers Flashcards
What is energy?
the quantity that must be changed or transferred to make something happen.
energy transfers and storage in running (6)
-At the start of the race you are stationary. The energy is stored in your toned-up muscles ready to be released.
-As you set off the energy from your muscles gets you moving.
-Your muscles store chemical energy. the energy stored by the chemicals in your muscles ready to be released at a moment’s notice.
-Your muscles start you moving and you then have kinetic energy. Running makes you hot.
-This tells us that some of the energy released in your muscles is wasted as thermal energy rather than becoming useful kinetic energy.
-Fitness training helps people to reduce this waste.
energy tranfers and storage in switching off the light (3)
-When you switch on the light the electricity meter starts to turn a little faster recording the fact that you are drawing more energy from the distant power station.
-Electricity is useful because it brings energy available at the flick of a switch.
-In the light bulb this energy is transferred by light.
-Every light bulb also produces thermal energy.
What is kinetic energy? (2)
-The energy store of a movng object.
-The faster the object move the greater its kinetic energy.
Gravitational potential energy (g.p.e)
-the energy stored in an object raised up against the force of gravity; more generally it is the distance between particles or bodies.
-The higher an object is above the ground the greater its gpe.
Eg of chemical energy stores (4)
-Fuels such as coal or petrol (gasoline) are stores of chemical stores.
-When fuel is turned the stored energy is released usually as heat and light.
-Batteries are also stores of energy. When a battery is part of a complete circuit the chemicals start to react with one another and an electric current flows.
-The current carries energy to the other components in the circuits.
Eg of nuclear energy stores (4)
-Uranium is an example.
-All radioactive materials are also stores of nuclear energy.
-In these substances, the energy is stored in the nucleus of the atoms- the tiny positively charged core of the atom.
-A nuclear power station is designed to release the nuclear energy stored in uranium.
Eg of strain energy/ elastic energy (2)
-When you stretch a rubber band, it can give this energy to a pellet and send it flying across the room.
-Strain energy is the energy stored by an object that has been stretched or squashed in an elastic way so that it will spring back to its original dimensions when the stretching or squashing forces are removed.
Eg of internal energy
-If you heat an object so that it gets hotter you are giving energy to its atoms.
-the energy stored in a hot object is called internal energy.
-The internal energy of an object is the total kinetic and potential energies of the particles it is made of.
-The internal energy of an object will be higher if these particles are moving faster (higher kinetic energy) or they are further apart (bigger potential energy).
Why doe heating an object increase its internal energy.
The internal energy of an object will be higher if these particles are moving faster (higher kinetic energy) or they are further apart (bigger potential energy). Therefore heating an object increases internal energy.
2 ways energy is transferred to their surroundings.
-Very hot objects glow brightly, they are transferring energy by light. Light radiates outwards all around the hot object.
-Sound is also another way energy gets transferred. An electric current transfers energy electrically to a loudspeaker. Energy is transferred to the surroundings as sound and thermal energy.
chemical energy
energy stored in bonds between atoms that can be released when chemical reactions take place.
nuclear energy
energy stored in the cucleus of an atom.
strain energy/ elastic energy
energy stored in the changed shape of an object.
internal energy
the energy of an object; the total kinetic and potential energies of its particles.
