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Physics > Section 2 - Conservation Of Energy > Flashcards

Section 2 - Conservation Of Energy Flashcards

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1
Q

The 8 different energy stores and what would fall into those categories

A

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

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2
Q

When’s Kenetic energy transferred to and away from a store?

A

When it speeds up it’s transferred to
When it slows down it’s transferred away

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3
Q

What does the energy in the kinetic energy store depend on?

A

Mass and speed of the object

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4
Q

The equation for kinetic energy is…

A

Ke=1/2 X m X v^2
Kinetic energy = half X mass X velocity ^2

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5
Q

Unit for kinetic energy ?

A

Joules (J)

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6
Q

What’s g.p.e

A

Gravitational potential energy

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7
Q

Why would more energy be transferred to the gravitational potential energy store?

A

If it’s lifted higher

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8
Q

What does the amount of energy in a gravitational potential energy store depend on?

A

Mass
Height
Strength of the gravitational field it’s in

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9
Q

Equation for gravitational potential energy…

A

GPE=m X g X h
Gravitational potential energy = mass X gravity X change in height

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10
Q

What does the conservation of energy mean?

A

It’s never created or destroyed, only transferred between stores and dissipated

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11
Q

Can a closed systems energy change?

A

The total energy in a closed system has no net change

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12
Q

If the energy of a system increases or decreases, what is it?

A

Not a closed system

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13
Q

The 3 ways energy is transferred…
What it is
Examples

A

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

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14
Q

An example of energy being transferred from store to store..

A

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

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15
Q

Diagram of energy being transferred

A
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16
Q

What energy transfer often involved losses?

A

Hearing

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17
Q

When’s energy only useful ?

A

When transfered from one store into another useful store

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18
Q

What’s happens to some of the input energy ?

A

Dissipated or wasted
Often into thermal energy stores of the surroundings

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19
Q

Diagram of energy being dissipated …

A
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20
Q

Equation for conservation of energy…

A

Total energy input = useful energy output + wasted energy

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21
Q

Equation for the efficiency of a device …

A

Efficiency = useful energy transferred by the device(J) / total energy supplied to the device

22
Q

Can the efficiency of a device be equal or more than 100%?

A

The efficiency of a device can never be equal to or be more than 100%

23
Q

What does the thickness of the arrow in a diagram of efficiency represent ?

A

How much energy is being transfered

24
Q

Where does wasted energy go on an efficiency diagram?

A

Splits of vertically downwards

25
Q

What’s a diagram of efficiency called?

A

A Sankey diagram

26
Q

2 ways of reducing wasted energy …

A

Lubrication
Insulation

27
Q

What does lubrication reduce energy transfered through?

A

Lubrication reduces energy transfered by friction

28
Q

Example of lubrication ?

A

Oil

29
Q

What does insulation reduce energy transfered through?

A

Insulation reduces energy transfer through heating

30
Q

Examples of insulation…

A

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

31
Q

2 categories of energy sources

A

Renewable
Non-renewable

32
Q

The 3 main fossil fuels …
Advantages
Disadvantages

A

Coal
Oil
(Natural) gas
Reliable
Do damages to the environment and will run out one day

33
Q

Examples of renewable energy sources
Advantages
Disadvantages

A

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

34
Q

What are solar cells
Adv
Disadvantages

A

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

35
Q

How does wind power work?
Advantages
Disadvantages

A

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

36
Q

What are biofuels and what are they made of?

A

Biofuels are renewable energy sources and they’re made from either plant products or animal dung

37
Q

Advantages of biofuels ?

A

-Carbon neutral
-Reliable as crops take a short time to grow and different crops can be grown all year round
-

38
Q

Disadvantages of biofuels …

A

-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

39
Q

What’s hydroelectricity ?

A

Producing hydroelectricity involves flooding a valley and building a big dam. Rainwater is caught and allowed through turbines

40
Q

Advantages of hydroelectricity?

A

-Minimal running costs
-reliable energy source
-no pollution
-can imidiatellt respond to increased energy demand. More water can be let out through the turbines

41
Q

What’s a tidal barrage?

A

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

42
Q

Advantages of tidal barrages?

A

-no pollution
-reliable as they’re dependant on the sun and moons gravity
-no fuel costs and minimal running costs

43
Q

Disadvantages of tidal barrages?

A

-Initial costs are moderately high
-effect boat access, spoil view and alter habitats

44
Q

Types of non renewable, reliable energy.

A

Fossil fuels
Nuclear energy

45
Q

Advantages of non renewable energy sources

A

-They have low costs, to run
- They can respond to changes in demand for energy quick

46
Q

Disadvantages of non renewable energy sources.

A

-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

47
Q

What is the use of renewables limited by?

A

Reliability and money

48
Q

What’s the aim of energy production?

A

Increase renewable energy use

49
Q

How to find KE?

A

KE = 1/2 X Mass X V^2

50
Q

How to calculate efficiency?

A

Efficiency= useful energy out / total energy in

Physics (7 decks)

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