Topic 1 - Energy Flashcards
(18 cards)
Define a closed system
A closed system is when a system does not allow any matter to leave or enter.
What are the four ways to transfer energy?
- – Electrically
- – Mechanically
- – By heating
- – By radiation
What are the eight energy stores?
- – Kinetic energy
- – Gravitational potential energy
- – Elastic energy
- – Chemical energy
- – Thermal energy
- – Electrosatic energy
- – Nuclear energy
- – Magnetic energy
What is the equation for kinetic energy?
Kinetic energy = 1/2mv^2
What is the equation for gravitational potential energy?
GPE = mgh
What is the equation for elastic potential energy?
Elastic potential energy = 1/2ke^2
What happens to the kinetic and gravitational potential energy as an object falls?
Loss in GPE = Gain in kinetic energy
What is the equation for specific heat capacity?
SHC = massspecific heat capacitychange in temperature
What is the conservation of energy principle.
Energy cannot be created or destroyed, it can only be transferred usefully, stored or dissipated.
What is the equation for power?
Power = energy / time
OR
Power = work done / time
What states of matter does conduction and convection occur in?
Conduction occurs in only solids. Convection occurs in liquids and gases.
Explain how conduction works.
When a soid is heated, energy is transferred to its thermal store. This energy is stored as the kinetic energy of the particles which causes the particles to vibrate on the spot. The particles vibrate and collide with the neighbouring particles. By colliding with neighbouring particles, energy is transferred. This process continues until energy is transferred to the other side of the object.
How do lubricants help to reduce unwanted energy transfers?
Lubricants reduce the friction between objects which means less energy is wasted or dissipated into the surroundings.
What are some examples of thermal insulation and give a brief description of each.
- – Draught excluders: placed around doors or windows to reduce transfers by convection
- – Cavity wall insulation: cavity wall air gap filled with foam to reduce transfers by convection
- – Loft insulation: reduces convection currents in lofts
- – Double-glazed windows: has an air gap to trap heat and reduces transfers by conduction
What is the general equation for efficiency?
Efficiency = useful output / total input
What is the difference between non-renewable and renewable energy resources?
Give examples of each.
Non-renewable resources will eventually run out whereas renewable resousrces will never run out because they are being replaced at the same rate that they are used up.
Non-renewable resources:
— Coal, Oil, Natural gas
Renewable resources:
— Wind, Solar, Tidal, Hydroelectric, Wave, Geothermal, Bio-fuel
What are the advantages and disadvantages of wind power?
Advantages:
- – No pollution
- – Minimal running costs due to no fuel costs
- – No permanent damage to landscape
Disadvantages:
- – Noise pollution
- – Visual pollution
- – Initial high costs
- – Unreliable as there is not always wind
What are the advantages and disadvantages of solar energy?
Advantages:
- – No visual pollution
- – No noise pollution
- – Minimal running cost
Disadvantages:
- – Unreliable as there is not always sun
- – High initial start up costs
