Energy Flashcards
What is energy
Energy is defined as the ability to do work
What units are used to measure energy
Joules
What is work done
Work is done when a force acts on an object and causes it to move through a distance in the direction of the force
What is the equation for work done
Work done = force * distance moved
How much work was done when a man lifted a 75kg bar 2 meters above the ground
Work done = (75*10) * 2
= 1500 J
How is work done related to energy transferred
Work done = Energy transferred
What are the eight energy stores
Gravitational Energy
Kinetic Energy
Elastic Energy
Thermal Energy
Chemical Energy
Magnetic Energy
Electrostatic Energy
Nuclear Energy
How do objects gain Gravitational Potential Energy
Objects gain G.P.E by moving higher
What is the equation for GPE
GPE (J) = mass (kg) * gravitational field strength * height
Name 2 objects that store G.P.E
An object on top of a shelf, an airplane flying
How do objects that store Kinetic Energy have the ability to do work
Objects that store kinetic energy have the ability to do work by changing their speed
What is the equation for kinetic energy
Kinetic energy = mass * speed^2 / 2
Name 2 objects that store K.E
A person running, A moving bike
How do objects that store elastic energy have the ability to do work
Objects that store elastic energy have the ability to do work by changing their shape
Name 2 objects that store elastic energy
A stretched bow, springs
Where is chemical energy stored
Chemical energy is stored in the bonds between the particles of the material
How do objects that store thermal energy have the ability to do work
Objects that store thermal energy have the ability to do work by changing their temperature
What is the difference between heat and thermal energy
Thermal energy is the energy stored in an object due to the movement of the particles it is made of, while heat is the amount of thermal energy transferred from a hot to a cold body
What is the principle of conservation of energy
Energy cannot be created or destroyed, it can only be transferred from one store to another
What are four ways of energy transfer
Mechanically
Electrically
By heating
By radiation
How is energy transferred mechanically
Energy is transferred mechanically when a force acts through a distance doing work
How is energy transferred electrically
Energy is transferred electrically through the flow of electric charge in an electric circuit
How is energy transferred by heating
Energy is transferred by heating from a hotter object to a colder one, resulting in the difference in temperature between them to decrease
How is energy transferred by radiation
Energy is transferred by waves through materials and from place to place
What is the equation for efficiency
efficiency = useful energy output / total energy input
Where is wasted energy transferred to
Wasted energy is transferred to the surroundings as thermal energy mechanically (by friction) or through heating (temperature difference)
What is power
Power is the rate of doing work
What is the equation for power
Power = Work done / time taken
What are the units of power
Watts
What are non-renewable energy sources
Non-renewable energy sources are those who cannot be replaced once they are used up
Give examples of fossil fuels
Coal
Oil
Natural Gas
What are the advantages of fossil fuels
More reliable as they are not weather dependent
High energy density
What are the disadvantages of fossil fuels
They will run out
Produce CO2 when burnt which causes global warming
Produce sulfur dioxide when burnt which causes acid rain
What are the advantages of nuclear fuels
No atmospheric pollution
Not weather dependent
High energy density
What are the disadvantages of nuclear fuels
Will run out
Difficult to dispose radioactive waste
Danger of nuclear accidents
High initial set up costs
What are renewable energy sources
Renewable energy sources are those that can be used repeatedly without running out
What are the advantages and disadvantages of renewable energy sources
Advantages:
They will not run out
They do not produce greenhouse gases
The fuel is usually free
Disadvantages:
Power stations have a high initial set up cost
What are some types of renewable energy sources
Solar energy
Tidal energy
Geothermal energy
Hydroelectric energy
Wind energy
Biomass
What are the advantages and disadvantages of solar energy
Advantages: Can be put on existing buildings
Disadvantages: Can be used only when sunny
Require a large area of panels
Visual pollution
What are the advantages and disadvantages of tidal energy
Advantages:
Disadvantages: Large areas of water must be enclosed, altering wildlife habitats
What are the advantages and disadvantages of geothermal energy
Advantages: Consistent power output
Doesn’t take up a lot of space
Disadvantages: Can only be built in areas of volcanic activity
What are the advantages and disadvantages of hydroelectric energy
Advantages: Not weather dependent
Disadvantages: Large dams have to be built, destroying natural habitats
It can only be used in wet regions
What are the advantages and disadvantages of wind energy
Advantages: Reduced running costs
Disadvantages: Noisy and unsightly
Only run when windy
Many generators are needed for sufficient energy
How is electricity produced
Stored energy (coal, oil, gas) is used to heat water and convert it into steam. This steam is used to drive and rotate the turbines that in turn spin a generator that produces electricity
What is conduction
Thermal conduction is the transfer of thermal energy through one or more substances that are in contact by the vibrations of the atoms within the substance
How is thermal energy transferred by conduction
When a part of a solid is heated, its particles start vibrating faster and collide with the particles of the colder part which are moving slower. When colliding, the faster moving particles transfer some of their kinetic energy to the slower moving ones, which gain kinetic energy and pass it on. This process is repeated causing temperature to increase
NOT ENTIRE CHAPTER
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