Across
- 3. the spreading out of energy into the environment, so that it is stored in less useful ways
- 5. a fundamental principle of physics: energy cannot be created or destroyed, only transferred, stored or dissipated. This means that the total energy of a closed system is constant.
- 6. the energy associated with a fuel (chemical energy store), heated object (thermal energy store), moving object (kinetic energy store), a stretched spring (elastic potential energy store) and an object raised above ground level (gravitational potential energy store)
- 9. energy that an object has because of its position; e.g., increasing the height of an object above the ground increases its gravitational potential energy
- 12. the energy needed to raise the temperature of 1 kg of a substance by 1 °C; symbol c, unit J/kg °C
- 13. energy that is stored in an object as a result of the object being stretched or compressed
- 16. source of energy that can be replaced or reused over a short time, e.g., biofuels from crops that can be grown again from seed
Down
- 1. the increase in length of an object when a force is applied
- 2. system that is not acted upon by any external forces and does not exchange energy with its surroundings
- 4. source of energy used by humans that will eventually run out (e.g., fossil fuels are non-renewable fuels)
- 7. energy an object has because of its movement; kinetic energy is greater for objects with greater mass or higher speed
- 8. process in which energy is moved from one store to another
- 10. the rate at which energy is transferred or the rate at which work is done; an energy transfer of 1 J/s is equal to a power of 1 W
- 11. useful output energy transfer divided by the total input energy transfer (or useful power output divided by the total power input) – may be expressed as a percentage or as a decimal
- 14. internal energy present in a system due to its temperature, which itself is due to the random motion of the particles within the system
- 15. SI unit of energy, symbol J