Topic P1-Energy Flashcards
What is the equation to work out the kinetic energy of an object?
Ek(J)=0.5Xm(kg) X speed2(m/s)
What is the equation for gravitational potential energy?
Ep=mass(kg) x gravitational field strength(kg) x height(m)
What is the equation that links efficiency, useful power output and total power input?
Efficiency = useful power output(W)/total power input(W)
What is the equation that links spring constant, elastic potential energy and extension?
Elastic potential energy(J)= 1/2 x spring constant(N/m) x extension(m)^2
What is the specific heat capacity of a substance?
The amount of energy required to raise the temperature of 1kg of the substance by 1C.
What is the equation that links change in temperature, specific heat capacity, mass and change in thermal energy?
Change in thermal energy(J) = Mass(kg) x specific heat capacity(J/kg) x change in temperature
What two equations can be used to calculate power?
Power(W) = energy transferred(J) / time(s)
Power(W) = work done(J) / Time(s)
What is conduction?
When an object is heated, energy is transferred to the kinetic energy stores of its particles.
This causes the particles to vibrate more, and to collide with each other. During these collisions, energy is transferred between the particles kinetic energy stores.
Do materials with a high thermal conductivity transfer energy between their particles at a faster rate or a slower rate?
Faster rate
What is convection?
Because liquids and gases can flow, the warmer and less dense region will rise above denser, cooler regions. So energetic particles move away from hotter to cooler regions.
What are a few things you can do to prevent energy losses through heating?
Have thick walls that are made from a material with a low thermal conductivity. This means the rate of energy transfer will be slower.
Use thermal installations e.g. double glazed windows and loft insulation.
How can you improve the efficiency of energy transfers?
Insulating objects.
Lubricating them.
Making them more streamlined.
What is the equation that includes efficiency, useful output energy transfer, and total input energy transfer?
Efficiency = useful output energy transfer / total input energy transfer
What is an example of something that uses renewable energy resources?
Vehicles that run on pure biofuels.
What are three examples of non renewable energy resources that we use to heat our homes?
Natural gas is used to heat water, which is then pumped into radiators throughout the home.
Coal is commonly burnt in fireplaces.
Electric heaters which use electricity generated from non-renewable energy resources.
What are three examples of renewable energy resources that we use to heat our homes?
A geothermal heat pump uses geothermal energy resources to heat buildings.
Solar water heaters work by using the Sun to heat water.
Burning biofuel, or using electricity generated from renewable resources.
What is one advantage and disadvantage of wind power?
Advantage – no permanent damage.
Disadvantage – 1500 win turbines are needed to replace one coal-fired power station.
What is an advantage and disadvantage of solar cells?
Advantage – there is no pollution.
Disadvantage – they generate electricity on a relatively small scale.
What is an advantage and disadvantage of geothermal power?
Advantage – reliable
Disadvantage – the cost of building a power plant is often high, compared to the amount of energy it produces.
