Energy Flashcards
What is energy?
Energy is responsible for things happening, and it can be stored in a variety of energy stores
How can energy be transferred?
Energy can be transferred through -
- heating
- waves
- electric current
- force
Can energy be created or destroyed?
No, energy cannot be created or destroyed, although it can be transferred
What is energy measured in?
Joules
Some energy stores are…
Elastic potential Chemical potential Gravitational potential Nuclear Internal Magnetic
Some energy transfers are…
Mechanical energy Light energy Sound energy Thermal energy Kinetic energy Electrical energy
What is work done?
Work done is when a force causes a body to move, so work is done on the body
What is the equation for work done?
Work done = Force x Distance moved in direction of force
What is the symbol equation for work done?
WD = FD
Note on work done…
One joule is the work done when a force of 1 Newton moves through a distance of 1 metre
Work done example…
If you have to exert an UPWARD FORCE of 10N in order to raise a book through a vertical distance of 1.5M, the work dome is 15J - this is also the amount of energy transferred
What is the formula for kinetic energy?
KE = 1/2MV^2
Kinetic Energy = 1/2 x Mass x Speed^2
What is the formula of Gravitational Potential Energy?
GPE = Mass x Gravitational field strength x (delta) Height
(Delta)GPE = MG(delta)H
What is important to consider when comparing fuels?
Energy Density
What is Power?
POWER is ENERGY TRANSFERRED per unit of TIME
What is the equation (Word and Symbol for Power)?
Power = Energy Transferred / Time
P = E / T
P = WD / T
What is the equation for Efficiency?
Efficiency = Useful energy transferred by the device / Total Energy
What are some reasons for devices wasting energy?
Devices waste energy through friction, resistance, air resistance and sound.
How can someone reduce energy wasted?
Lubricate moving parts, Use wires with little electrical resistance, streamline shapes to counter air resistance, cut out noise by reducing vibration
What is a renewable energy resource?
One that is replenished as it is used
What are some uses of energy resources?
Transport, electrical energy use in homes, thermal use for heating
What is the equation for elastic potential energy?
Ep = 1/2ke^2
What is the unit for a spring constant?
N/m
Why might motors have a high kinetic energy?
Because it has a high power
What is a biofuel?
A renewable, carbon neutral fuel obtained from a living or recently living organism
How does a wind turbine work?
- Wind passes over turbine blades
- Making the turbines rotate
- Which drives a generator
- Producing electricity
How does a wave generator work?
- Waves rock a floating turbine
- Moving turbine up and down
- Generating electricity
How is geothermal energy harvested?
- Comes from energy released deep from within Earth
- Energy heats up surrounding rocks
- Deep holes are drilled and water is pumped down
- Water comes back to surface as steam
- Which is used to drive turbines
How do solar cells work?
- Transfers energy through EM radiation from Sun
- Straight into electricity
- So very useful to power small devices
- Such as watches
Renewable Energy resources advantages
- Wil never run out
- Do not cause environmental harm
Renewable Energy resources disadvantages
- Cannot currently meet world energy demand
- Unreliable
What is the specific heat capacity?
The energy required to heat 1kg of a substance by 1°C
How can we reduce energy wasted in houses?
- Fibreglass loft insulation reduces rate of energy transfer through the roof
- Cavity wall insulation reduces rate of energy transfer through walls
- Aluminium foil behind radiators reflects radiation back into the room
- Double glazed windows reduces rate of energy transfer through windows
- Thick, low conductivity bricks reduces rate of energy transfer through outer walls
Advantages of Nuclear Power
- Do not produce greenhouse gases
- Transfer much more energy per kilogram than fossil fuels
Disadvantages of Nuclear Power
- Radioactive waste is a biproduct that must be stored fore years
- Accidents can happen putting lives at risk
Equation for Efficiency?
Useful output energy transfer / Total input energy transfer
