Physics : Conservation of Energy Flashcards
(49 cards)
What are energy stores?
Different ways to store energy
What is the kinetic energy store?
Anything moving has energy in it’s kinetic store
What is the gravitational potential energy store?
anything in a gravitational field (i.e. anything that can fall)
If an object is raised above the Earth’s surface, what store is the energy in?
It will have energy in its gravitational potential store
What is the thermal energy store?
any object has a thermal energy store - the hotter the object gets, the more energy it has in its store
What is the elastic potential energy store?
anything stretched, like springs, rubber bands, etc.
What is the electrostatic energy store?
e.g. two charges that attract or repel each other
What is the magnetic energy store?
e.g. two magnets that attract or repel each other
What is the equation to calculate kinetic energy?
Kinetic energy (J) = 0.5 x
mass (kg) x (speed)^2 (m/s)^2
KE = 0.5 x m x v^2
What is the conservation of energy?
Energy can be stored , transferred between stores and dissipated - but it can never be created or destroyed. The total energy of a closed system has no net change
What is the nuclear energy store?
atomic nuclei release energy from this store in nuclear reactions
What is the chemical energy store?
anything that can release energy by a chemical reaction e.g. food, fuels
If an object is moving what store is its energy in?
It will have energy in its kinetic energy store
What is the equation to calculate the change in gravitational potential energy?
Change in gravitational potential energy = mass x gravity x change in height
GPE = m x g x h
What are the 4 energy transfers?
Mechanically, electrically, by heating and by radiation
When is energy only useful?
Energy is only useful when it is transferred from one store to a useful store
How can energy be transferred electrically?
A charge doing work, e.g. charges moving round a circuit
How can energy be transferred mechanically?
A force acting on an object, e.g. pushing, stretching, squashing
How can energy be transferred by heating?
Energy transferred from a hotter object to a colder object, e.g. heating a pan on a hob
What equation is used to find the total energy output?
total output energy = useful energy output + wasted energy
How can energy be transferred by radiation?
Energy transferred by waves, e.g. energy from the Sun reaching Earth by light
What can be used to reduce the wasted energy transfer due to friction?
A lubricant can be used to prevent friction by allowing the surfaces to move smoothly
How do you calculate the efficiency of an energy transfer?
Efficiency = useful transferred (J) / total energy input (J)
What can be used to reduce the wasted energy transfer due to heating?
By insulating a wall or leaving an air gap, it reduces the conduction and so slows the rate of energy transfer preventing heat energy from moving
