Conservation Of Energy Flashcards
(26 cards)
Kinetic
Anything moving has energy in its kinetic energy store
Thermal
Any object- the hotter it is the more energy it has in this store
Chemical
Anything that can release energy by a chemical reaction (food, muscles, fuels)
Gravitational Potential
Anything inside a gravitational field (something that can fall) (roller coster at the top, aero plane)
Elastic
Something that can be stretched twisted squashed (rubber, springs)
Magnetic
Two magnets that attract or repel each other
Like poles unlike poles
Electrostatic
Two charges that attract or repel each other
Nuclear
Atomic nuclei release energy from this store in nuclear reactions
Mechanically
An object moving due to a force acting on it (push pull)
Electrically
A charge moving due to a potential difference (charges moving around a circuit)
By heating
Energy transfer from a hotter object to a colder object.
By radiation
Energy transfer by waves (light or sound waves) (energy from the sun reaching the Earth
Principal of conservation of energy
Energy can’t be created or destroyed it changes from one store to another.
Total energy input=
Useful energy output + wasted energy
Efficiency=
Useful energy output/ total energy output x 100
Conduction
Thermal conduction is the process where vibrating particles transfer energy from their kinetic energy store to the kinetic energy store of neighbouring particles.
(Experiment Bunsen burner metal bar attached with breads)
Convection
Convection occurs when the more energetic particles move from the hotter region as they are less dense to the colder regions and become more dense- and transfer energy as they do so.
Convection current is
When you heat the water or air particles and they become less dense meaning that they are going to rise and in the process collide with other more dense colder particles and transfer their energy making them more dense and cooler and as a result the dense particles will sink again. This process will be repeated constantly.
Radiation
Transfer of energy through waves. Eg. Sound or light waves
To reduce conduction use
Materials with low thermal conductivity such as plastic or wood
To reduce convection
Stop the fluid from moving and use a insulator (cloths or blankets) to reduce the energy
To reduce radiation
The object should be designed with a surface that is a poor emitter such as white or shiny.
If it’s black or it’s not going to reduce the radiation, as black is a good emitter and white a good reflector.
Work done =
Force x distance moved
Power=
Work done / Time taken
