Energy Flashcards
Name the types of energy store:
Thermal Kinetic Gravitational potential Elastic potential Chemical Magnetic Electrostatic Nuclear
Is energy a closed or open system?
Energy is transferred in a closed system so it can not enter or leave do the net change will always be zero and energy can never be destroyed
Work done
Is another way of saying energy transferred and is done when a current flows or by a force of an object.
Work done : force x distance
Do Falling objects transfers energy
Yes
Falling objects transfer energy
If a ball is dropped from a height it’s accelerated by gravity and does work. The energy from its gravitational potential energy is transferred to its kinetic energy store
Kinetic energy is anything moving
What is the equation for kinetic energy?
E=1/2mv2
Kinetic energy = 1/2mass x speed2
Lifting an object in a gravitational field requires work what is the equation to calculate gravitational potential energy
E=mgh
GPE=mass x gravitational field strength x height
What is the gravitational field strength on earth?
9.8
Stretching an object can transfer energy to elastic potential energy stores
To find the elastic potential in a stretched object you use
E=1/2ke2
Elastic potential energy=1/2spring content x extension2
Different materials have different specific heat capacity’s what is a specific heat capacity?
The amount of energy needed to raise the temperature of a substance by 1degree
What is the formula involving specific heat capacity?
Change in thermal energy = mass x specific heat capacity
How to investigate specific heat capacity
1: Get a block of your material with two holes in it
2: Measure the mass of the block and wrap it in an insulating material
3: measure initial temperature then turn on power supply heating material and start timer
4: use the thermometer to measure rise every minute a
5: once you have enough recordings calculate the SHC
Power is the rate of doing work and us measured in watts.
What is the equation for power?
P=E/T or P=W/T
Power = energy transferred / time
Power = work done / time
What is conduction?
Conduction is the process where vibrating particles transfer energy to neighbouring particles
It mainly occurs in solids
What is Convection?
Convection is where energetic particles move away from hotter to cooler regions
It only occurs in liquids and gases
Why do solids not do convection?
Solids can’t do convection because unlike in gases and liquids the particles are not free to live and so the density doesn’t change
How does lubrication reduce frictional forces?
Lubricants are used to make surfaces smoother and more easy to move. They reduce friction as they are liquids and easily slide between objects.
What does insulation do?
Insulation reduces the rate of energy transfers by heating as it has low thermal conductivity so the rate of transfers is slower. This means a house for example would lose heat more slowly so it is insulated.
How do cavity walls work?
Cavity walls are made of an inner and outer wall with an air gap in the middle. Because conduction can’t occur in the air it reduces the conduction. If there is then foam put in the wall convection Is also stopped to the wall is an insulator.
How to investigate effectiveness of different insulators?
1: Boil a kettle and pour the water into a sealable container.
2: use a thermometer to measure the initial temp
3: seal container and leave for 5 mins and then record the temperature.
4. Repeat the experiment with your chosen insulators wrapped around the container.
How do you calculate efficiency?
Efficiency = useful output energy transfers/total input energy transfer
Most devices aren’t 100% energy efficient but some are name one:
Electric heaters as app the energy is electrostatic and transferred to thermal
What is a non renewable energy resource and name some:
A fossil fuel or nuclear fuel that form underground and will run out as they can’t be reused
Eg
Coal
Oil
Gas
What are renewable energy resources?
Resources that will never run out
Eg Solar energy Wind Water wagers Bio fuel Tides Geothermal
Non renewable resources are very damaging to the environment and cause a lot of green house gases when they are burned so what must we do
We must replace them with renewable energy sources that are less damaging and won’t run out
