Section 2 - Conservation Of Energy

Question 1

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

Answer 1

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

Question 2

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

Answer 2

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

Question 3

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

Answer 3

Mass and speed of the object

Question 4

The equation for kinetic energy is…

Answer 4

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

Question 5

Unit for kinetic energy ?

Answer 5

Joules (J)

Question 6

What’s g.p.e

Answer 6

Gravitational potential energy

Question 7

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

Answer 7

If it’s lifted higher

Question 8

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

Answer 8

Mass
Height
Strength of the gravitational field it’s in

Question 9

Equation for gravitational potential energy…

Answer 9

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

Question 10

What does the conservation of energy mean?

Answer 10

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

Question 11

Can a closed systems energy change?

Answer 11

The total energy in a closed system has no net change

Question 12

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

Answer 12

Not a closed system

Question 13

The 3 ways energy is transferred…
What it is
Examples

Answer 13

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

Question 14

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

Answer 14

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

Question 15

Diagram of energy being transferred

Answer 15

Question 16

What energy transfer often involved losses?

Answer 16

Hearing

Question 17

When’s energy only useful ?

Answer 17

When transfered from one store into another useful store

Question 18

What’s happens to some of the input energy ?

Answer 18

Dissipated or wasted
Often into thermal energy stores of the surroundings

Question 19

Diagram of energy being dissipated …

Answer 19

Question 20

Equation for conservation of energy…

Answer 20

Total energy input = useful energy output + wasted energy

Question 21

Equation for the efficiency of a device …

Answer 21

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

Question 22

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

Answer 22

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

Question 23

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

Answer 23

How much energy is being transfered

Question 24

Where does wasted energy go on an efficiency diagram?

Answer 24

Splits of vertically downwards

Question 25

What’s a diagram of efficiency called?

Answer 25

A Sankey diagram

Question 26

2 ways of reducing wasted energy …

Answer 26

Lubrication Insulation

Question 27

What does lubrication reduce energy transfered through?

Answer 27

Lubrication reduces energy transfered by friction

Question 28

Example of lubrication ?

Answer 28

Oil

Question 29

What does insulation reduce energy transfered through?

Answer 29

Insulation reduces energy transfer through heating

Question 30

Examples of insulation…

Answer 30

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

Question 31

2 categories of energy sources

Answer 31

Renewable Non-renewable

Question 32

The 3 main fossil fuels … Advantages Disadvantages

Answer 32

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

Question 33

Examples of renewable energy sources Advantages Disadvantages

Answer 33

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

Question 34

What are solar cells Adv Disadvantages

Answer 34

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

Question 35

How does wind power work? Advantages Disadvantages

Answer 35

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

Question 36

What are biofuels and what are they made of?

Answer 36

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

Question 37

Advantages of biofuels ?

Answer 37

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

Question 38

Disadvantages of biofuels …

Answer 38

-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

Question 39

What’s hydroelectricity ?

Answer 39

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

Question 40

Advantages of hydroelectricity?

Answer 40

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

Question 41

What’s a tidal barrage?

Answer 41

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

Question 42

Advantages of tidal barrages?

Answer 42

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

Question 43

Disadvantages of tidal barrages?

Answer 43

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

Question 44

Types of non renewable, reliable energy.

Answer 44

Fossil fuels Nuclear energy

Question 45

Advantages of non renewable energy sources

Answer 45

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

Question 46

Disadvantages of non renewable energy sources.

Answer 46

-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

Question 47

What is the use of renewables limited by?

Answer 47

Reliability and money

Question 48

What’s the aim of energy production?

Answer 48

Increase renewable energy use

Question 49

How to find KE?

Answer 49

KE = 1/2 X Mass X V^2

Question 50

How to calculate efficiency?

Answer 50

Efficiency= useful energy out / total energy in