Unit 3 - Conservation Of Energy Flashcards
What is the energy stored in food, fuel and batteries called?
Chemical energy
What is kinetic energy?
Energy stored in moving objects
What energy is in hot objects?
Thermal energy
What is strain or elastic potential energy?
Energy stored in squashed, twisted or stretched materials
What energy is stored in high positioned objects?
Gravitational potential energy
What energy is stored in atoms?
Atomic energy or nuclear energy
What is the law of conservation of energy?
It means that energy can only be transferred from one object to another. The total energy in is the total energy out.
What is energy measured in?
Joules (J)
What does a sanity diagram show?
How much energy transferred is useful and how much is waste.
What does dissipated mean?
Spread out
What does lubrication mean?
When a substance is added to minimise friction and allow smooth movement.
Give an example of a lubricant
Oil
What is efficiency?
A way of describing how well a machine is at transferring energy info useful forms. It is a number between 0 and 1
How can you calculate the efficiency?
Efficiency = Useful energy
————–
Total energy
Define insulation
When a material is used to stop heat, sound or electricity for transmitting.
What happens in conduction?
Vibrations are passed on between particles in a solid
What is a thermal conductor?
A material that transfers heat energy well.
What is a good thermal insulator?
A material that stop the heat from spreading.
What happens in convection?
Part of a fluid is warmer than the rest causing it to rise which creates a conversation current.
What happens in radiation?
This is the only way energy can be transferred through a vacuum. Infrared radiation is absorbed and emitted easily by dark surfaces and is absorbed and emitted poorly by light surfaces.
What does emitted mean?
Give out
Why is air a good insulator?
Air has a very low thermal conductivity so when it is trapped, it cannot form convection currents so it doesn’t transfer much energy.
What can effect the rate in which energy is transferred?
The thickness of the material, thermal conductivity, temperature difference across.
How does an object contain more GPE?
When it is moved upwards, further away from the surface of the earth.
How can GPE be calculated?
Change in GPE = mass x gravitational x change in height.
field strength
How can kinetic energy be calculated?
Kinetic energy = 0.5 x mass x velocity
What are nuclear fuels?
They store a lot of energy in a small piece of material.
Why are nuclear fuels very useful in spacecrafts?
It allows the fuel to be lightweight.
What does non-renewable mean?
One day it will run out.
What is a fossil fuel?
A natural fuel such as coal, oil or gas formed in the past from remains of living organisms.
What is petrol and diesel used for and why?
Vehicles, aeroplanes and ships. They store a lot of energy and they are easy to store and use in engines.
What is natural gas used for?
It is burnt to heat homes and for cooking.
Why is burning fossil fuels bad?
It releases carbon dioxide and other gases which contributes to climate change. It can also cause further pollution problems.
Why is burning natural gas better?
It causes less pollution and release less carbon dioxide.
What do nuclear power stations release?
Radioactive waste.
Give two negatives about nuclear power stations.
The radioactive waste is expensive to dispose safely. It is very expensive to dismantle safely and to build.
What are renewable resources?
Resources of energy that will never run out.
Why are countries deciding to use more renewable resources?
They will help reduce pollution and the supply of fuels will last longer. No fuel is burned.
How does solar energy work?
Solar panels are used to convert energy from the sun into electrical energy but it is not always available.
How does hydroelectricity work?
Electricity is generated by falling water in places where water can be trapped in high reservoirs. A turbine is turned by the water and the generator converts the energy into electricity.
How do wind turbines work?
A rotating generator converts wind energy into electricity. This relies on the amount of wind.
How does tidal energy work?
Turbines in huge dams across a river turn as the tides flow in and out. A generator then converts the energy into electricity.
What are bio-fuels?
Fuels that can be used in the same ways as fossil fuels but are made from animal wastes or from plants.
Why are bio-fuels carbon neutral?
They release the same amount of carbon dioxide as they took in.
Why might bio-fuels not be carbon neutral?
Energy is needed to grow, harvest and turn them into fuel.
Why can’t we only use renewable resources?
They are not always available and they take up a lot of land.
