Energy Resources And Energy Transfer - Part 3 (T4)

Question 1

A Ferrari has a mass of 960kgs and can produce a KE of 3,800,000 J. How fast can it go?

Answer 1

KE = 1/2 x m x v squared

v squared = 2 x 3,800,000 / 960

= 89.0 m/s to 3 significant figures

Question 2

What does the law of conservation of energy tell us about falling objects?

Answer 2

Falling objects convert all their gravitational potential energy into kinetic energy by the time they hit the ground

Question 3

What equations do we use to calculate the speed of falling objects?

Answer 3

1/2 x m x v squared = m x g x h

• mass appears on both side so we can cancel it out

1/2 x v squared = g x h

• rearrange as follows:

V squared = 2 x g x h

Question 4

Explain the history of the unit of energy; the Joule

Answer 4

• the unit of energy is names after James Joule (1818-1889)
• he realised that heat was a form of energy and showed that kinetic energy could be converted into heat
• before, it was measured in calories
• in 1843 he worked out the “mechanical equivalent of heat”

Question 5

List five main types of renewable energy..

Answer 5

• wind turbines
• hydroelectric power
• tidal and wave power
• geothermal energy
• solar heating

Question 6

Describe wind turbines..

Answer 6

• wind turbines convert the kinetic energy of the wind into electrical energy
• however, energy is still lost in a variety of ways..
• not all of the wind’s kinetic energy is used in the process so the wind still has some velocity after passing through the turbine
• frictional and electrical heating losses in the generator account for the rest of the energy loss, as well as a tiny amount of sound energy

Question 7

How does hydroelectric power work?

Answer 7

• hydroelectric power converts gravitational potential energy stored into a reservoir into kinetic energy and then into electrical energy
• in the Uk it is only really used in short bursts, to help cope with sudden increases in demand for electricity at peak times
• this is because there is not enough energy available for sustained production at a useful level unless you have schemes on a much larger scale than we are currently capable of developing in this country

Question 8

Describe tidal and wave power…

Answer 8

• installations vary from small water wheels to large barriers across river estuaries
• in the UK we have the potential to generate a lot of power this way but it would involve huge civil engineering projects and potential destruction of seashore habitats so at the moment our tidal and wave power installations are quite modest

Question 9

Describe geothermal energy..

Answer 9

• this is the heat stored in the Earth’s lower layers
• it is currently only viable in areas where the Earth’s crust is thin, generally volcanic regions
• they drill two holes down to a hot region then set off an explosion between the bottom of the two holes
• cold water is then sent down into one of the holes and hot steam comes up through the other
• the steam is used to drive a turbine attached to a generator which produces electricity
• to so the energy conversion is from heat to kinetic to electrical
• this is a very environmentally friendly method of producing electricity
• it is also very cheap
• the UK has some potential sites but is largely unexploited as yet
• Iceland gets most of its electricity this way

Question 10

Describe solar heating systems…

Answer 10

• there are two types of solar panels, with the most common being the photovoltaic cell type which converts light directly into electricity
• another type is the water heater, which involved water running through pipes that are painted Matt black or have fins on them
• the pipes have insulation behind them and are sometimes put inside a sealed container that has a glass front and a vacuum inside to help prevent heat losses by conduction or convection
• the sun’s infrared Rays heat the water in the pipes which can then be used for heating the home or hot water

Question 11

How does burning fossil fuels negatively affect the environment?

Answer 11

• burning fossil fuels releases carbon dioxide into the atmosphere
• burning coal releases more CO2 than oil or gas
• CO2 is a member of the greenhouse gases, which trap the sun’s heat in the Earth’s atmosphere and help cause what is known as global warming
• most types of coal and oil contain sulphur and when they are burned this is converted to sulphur dioxide
• sulphur dioxide is then released into the atmosphere where it can combine with water to form acid rain

Question 12

How is electricity in today’s power stations presently generated?

Answer 12

• heat from nuclear fuel or from burin in fossil fuels is used to heat water
• this produces high pressure steam that makes the blades of a turbine spin
• a turbine is like a windmill or a fan but with more blades
• the turbine is used to turn the generator, which generates electricity

Question 13

Why is the power generated from nuclear processes considered “clean” and what are some of the disadvantages of using nuclear power?

Answer 13

• power generated from nuclear processes is considered because the process does not involve the production of greenhouse or other polluting gases
• the cost per unit of electricity is also very low

However…

• nuclear power stations are expensive to build
• the risk of accidents are a concern
• disposal of nuclear waste is a problem
• if accidentally released, materials like uranium and plutonium can cause long lasting risks to living organisms

Question 14

Explain why nuclear power is still currently an example of a non-renewable source…

Answer 14

• nuclear reactors use uranium to produce energy
• for nucleus purposes a particular isotope is needed
• Uranium in the Earth was formed before the solar system was formed, so once it is used up there will be no further supplies