Energy Flashcards
What is the equation for energy efficiency?
useful energy/total energy x100
Define renewable energy sources
Resources that are able to last indefinitely without any reduction in supply. Replaced through natural processes quicker than they are being used.
What is nuclear energy? How does it work?
Using Uranium to produce electricity. Works by a neutron striking the uranium, splitting it which releases heat, heats water, steam, turbine, generator, electricity
Define nonrenewable energy sources
Exists only in limited deposits across earth. Cannot be replaced at a level equal to or greater than the rate at which it is being used.
What is biomass fuel?
Energy derived from material produced by living things
Define kinetic energy
Energy associated with the movement of an object or particles.
Define potential energy
‘Stored’ energy that can be released to perform work
Define chemical energy
Potential energy stored in the bonds of chemical compounds
What is energy?
The capacity to perform work
How do you calculate useful energy?
- The amount of work done
2. Energy input - energy lost
Equation for energy? (joules)
Power (watts) x time (seconds)
What is a nonrenewable, non-fossil fuel energy source?
Nuclear
What is the equation for power? (watts)
Energy (joules)/time(seconds)
What are the two different categories of renewable energy?
- Those that are infinite and available irrespective of rate of use (wind)
- Those that are renewable as long as their rate does not exceed their rate of replenishment (eg wood)
What is a fuel?
A substance that contains chemical energy that is released when oxidised
What is an energy source?
Naturally occurring fuels or sources of energy that can be converted into useful forms
Define endothermic and exothermic reactions
Exo - releases energy
Endo - takes up energy
What is power?
The amount of energy used or available over a given period of time
What is a joule?
A unit of energy that can:
- Heat up 1cm^3 of water by 0.25*C
- Lift 100g mass by 1cm
What is temperature
The average kinetic energy of molecules within a material or substance.
Second law of thermodynamics?
No conversion of energy is 100%. Some energy is always degraded to a less usable energy form (usually heat)
First law of thermodynamics?
Energy is neither created nor destroyed, merely changed from one form to another
One kilojoule is how many times bigger than a joule?
1000
Difference between black and brown coal? Which is cleaner?
Black is more efficient bc brown coal has higher water content
What is a fossil fuel?
A fuel formed from organic matter put under large amounts of heat and pressure due to being buried under sediment or rocks for long geological periods of time.
Define combustion
The reaction of a fuel with oxygen resulting in the release of energy
Define mechanical energy
The amount of energy possessed by an object due to it’s movement and it’s position. Conversion of potential energy into other forms of energy involving movement
What is a watt?
One joule per second
