Energy Flashcards
Name four energy stores.
Thermal, kinetic, grav. potential, elastic potential, chemical, magnetic, electrostatic, nuclear
Describe the energy transfers that occur as a ball falls to the ground.
The ball is accelerated by gravity - the gravitational force does work. It causes energy to be transferred from the ball’s grav. potential store to its kinetic energy store.
Give the equation for finding the energy in an object’s kinetic energy store.
Kinetic Energy = 1/2 x mass x (speed)²
If energy is transferred to an object’s kinetic energy store, what happens to its speed?
It will increase.
Give the equation for finding the energy in an object’s gravitational potential energy store.
GPE = mass x gravitational field strength x height
What kind of energy store is energy transferred to when you compress a spring?
Elastic potential.
What is the definition of the specific heat capacity of a material?
The amount of energy needed to raise the temperature of 1kg of a substance by 1°.
Give the equation that relates energy transferred and specific heat capacity,
Change in thermal energy = mass x specific heat capacity x temperature change
State the conservation of energy principle.
Energy can be transferred usefully, stored or dissipated, but can never be created or destroyed.
Define power.
The rate of energy transfer, or the rate of doing work.
Give two equations to calculate power.
Power = energy transferred / time Power = work done / time
What are the units of power?
Watts
How can you reduce unwanted energy transfers in a machine with moving, touching components?
Lubrication
True or false? A high thermal conductivity means there is a higher rate of energy transfer.
True
Give four ways to prevent unwanted energy transfers in a home.
Loft insulation
Double-glazed windows
Draught excluders
Cavity walls
True or false? Thicker walls make a house cool down quicker.
False
What is the efficiency of an energy transfer?
The percentage of energy input that is actually useful.
Give the equation that relates efficiency to power.
Efficiency = useful power input / total power input
Name four renewable energy resources.
The sun, wind, water waves, hydro-electricity, bio-fuel, tides, geothermal
Name three non-renewable energy resources.
Coal, oil, natural gas
What is the difference between renewable and non-renewable energy resources?
Renewable energy resources will never run out, but non-renewable resources will run out eventually.
Give an example of how a renewable energy resource is used in everyday life.
Vehicles that run on bio-fuels
Explain why solar power is considered to be a fairly reliable energy resource.
In sunny areas where there’s not much variation in the weather, solar panels are reliable in supplying power during the sunlight hours.
Give two ways in which the environment can be damaged when using fossil fuels.
Fossil fuels release CO2 into the atmosphere, which contributes to global warming.
Burning coal and oil releases sulphur dioxide into the atmosphere, which causes acid rain.
