Section 2 - Conservation Of Energy Flashcards
The 8 different energy stores and what would fall into those categories
Thermal- anything hot, the hotter the more energy it has in this store.
Kinetic- anything moving has energy in this store.
Gravitational potential- anything in a gravitational field (can fall)
Elastic- anything stretched, like springs,rubber bands
Chemical- anything that can release energy by a chemical reaction
Magnetic - eg: two magnets that attract and repel Eachober
Electrostatic- eg: two charges that attract and repel Eachober
Nuclear - atomic nuclei release energy from this store in nuclear reactions
When’s Kenetic energy transferred to and away from a store?
When it speeds up it’s transferred to
When it slows down it’s transferred away
What does the energy in the kinetic energy store depend on?
Mass and speed of the object
The equation for kinetic energy is…
Ke=1/2 X m X v^2
Kinetic energy = half X mass X velocity ^2
Unit for kinetic energy ?
Joules (J)
What’s g.p.e
Gravitational potential energy
Why would more energy be transferred to the gravitational potential energy store?
If it’s lifted higher
What does the amount of energy in a gravitational potential energy store depend on?
Mass
Height
Strength of the gravitational field it’s in
Equation for gravitational potential energy…
GPE=m X g X h
Gravitational potential energy = mass X gravity X change in height
What does the conservation of energy mean?
It’s never created or destroyed, only transferred between stores and dissipated
Can a closed systems energy change?
The total energy in a closed system has no net change
If the energy of a system increases or decreases, what is it?
Not a closed system
The 3 ways energy is transferred…
What it is
Examples
Mechanically - a force acting on an object eg: stretching
Electrically - a charge doing work eg: charges moving around a circuit
Radiation - energy transfers by waves eg: energy from the sun reaching earth by light
An example of energy being transferred from store to store..
A ball rolling up a slope
The ball does work against gravitational force, so energy is transferred mechanically from the kinetic energy store of the ball to the gravitational potential energy store
Diagram of energy being transferred
What energy transfer often involved losses?
Hearing
When’s energy only useful ?
When transfered from one store into another useful store
What’s happens to some of the input energy ?
Dissipated or wasted
Often into thermal energy stores of the surroundings
Diagram of energy being dissipated …
Equation for conservation of energy…
Total energy input = useful energy output + wasted energy
Equation for the efficiency of a device …
Efficiency = useful energy transferred by the device(J) / total energy supplied to the device
Can the efficiency of a device be equal or more than 100%?
The efficiency of a device can never be equal to or be more than 100%
What does the thickness of the arrow in a diagram of efficiency represent ?
How much energy is being transfered
Where does wasted energy go on an efficiency diagram?
Splits of vertically downwards
What’s a diagram of efficiency called?
A Sankey diagram
2 ways of reducing wasted energy …
Lubrication
Insulation
What does lubrication reduce energy transfered through?
Lubrication reduces energy transfered by friction
Example of lubrication ?
Oil
What does insulation reduce energy transfered through?
Insulation reduces energy transfer through heating
Examples of insulation…
Loft insulation layed out on the loft floor
Double glazed windows have an air gap between two sheets of glass to prevent energy transfer by conduction through the windows
2 categories of energy sources
Renewable
Non-renewable
The 3 main fossil fuels …
Advantages
Disadvantages
Coal
Oil
(Natural) gas
Reliable
Do damages to the environment and will run out one day
Examples of renewable energy sources
Advantages
Disadvantages
1.The sun (solar)
2.Wind
3.Hydroelectricity
4.Bio-fuel
5.Tides
They will never run out
Less damage to the environment
They don’t provide much energy and some depend on the weather so are unreliable
What are solar cells
Adv
Disadvantages
Made from materials that use energy transfered by light to create an electric current. Often used in remote places where there’s not much choice
Dis-.initial costs are high small scale. Only works well in sunny countries.doesnt work at night
Adv- basically no running costs. Low pollution
How does wind power work?
Advantages
Disadvantages
1)Each wind turbine has a generator inside it- wind rotates the board which turn the generator to produce electricity
Disadvantages-initial costs are quite high. Lots needed to produce power. Spoil the view and are noisy. Onlywork then it’s windy
Advantages - running costs are minimal
What are biofuels and what are they made of?
Biofuels are renewable energy sources and they’re made from either plant products or animal dung
Advantages of biofuels ?
-Carbon neutral
-Reliable as crops take a short time to grow and different crops can be grown all year round
-
Disadvantages of biofuels …
-The cost to refine biofuels is very high.
-large areas of the forest have been cleared to make room to grow biofuels, resulting in loss of animal habitats
What’s hydroelectricity ?
Producing hydroelectricity involves flooding a valley and building a big dam. Rainwater is caught and allowed through turbines
Advantages of hydroelectricity?
-Minimal running costs
-reliable energy source
-no pollution
-can imidiatellt respond to increased energy demand. More water can be let out through the turbines
What’s a tidal barrage?
Big fans built across river estuaries with turbines in them
As tide comes in it fills up the estuary, the water is then let out through the turbines to generate electricity
Advantages of tidal barrages?
-no pollution
-reliable as they’re dependant on the sun and moons gravity
-no fuel costs and minimal running costs
Disadvantages of tidal barrages?
-Initial costs are moderately high
-effect boat access, spoil view and alter habitats
Types of non renewable, reliable energy.
Fossil fuels
Nuclear energy
Advantages of non renewable energy sources
-They have low costs, to run
- They can respond to changes in demand for energy quick
Disadvantages of non renewable energy sources.
-release c02 into the atmosphere, this adds to the greenhouse effect and contributes to global warming
-Releases sulfur dioxide which causes acid rain.
-Nuclear waste is difficult to dispose of
-nuclear power always has the risk of a major catastrophe eg: Chernobyl
What is the use of renewables limited by?
Reliability and money
What’s the aim of energy production?
Increase renewable energy use
How to find KE?
KE = 1/2 X Mass X V^2
How to calculate efficiency?
Efficiency= useful energy out / total energy in
