Topic 3 - Conservation of Energy

Give 2 advantages of solar power

No carbon dioxide/greenhouse gases released. Renewable, reduces household energy bills

Give 2 disadvantages of solar power

Not reliable power output as sun is not always shining (e.g overnight), Expensive to install.

Give 2 advantages of fossil fuels.

Reliable output which does not depend on location or weather. Fuel has a relatively low cost and is easy to extract.

Give 2 disadvantages of fossil fuels

Releases CO2 when burnt which contributes to the greenhouse effect. Extraction (mining/fracking) can cause environmental damage.

Give 2 advantages of bio-fuel

Replacement plants can be grown very quickly to ensure a good supply. Net zero carbon dioxide released by process.

Give 2 disadvantages of bio-fuel

Land used for energy crops may be needed for other purposes such as agriculture. Atmospheric pollution created when burnt.

Give 2 advantages of hydroelectricity

No CO2/greenhouse gases released, renewable and sustainable

Give 2 disadvantages of hydroelectricity

Construction of dam is expensive, flooding the valley affects wildlife negatively

Give 2 advantages of wind

No CO2/greenhouses gases emitted, renewable resource, no cost for wind and low running costs.

Give 2 disadvantages of wind.

Not a reliable output as wind is not blowing all the time. Cost to build and install them is high. Some people think they are an eyesore

Give 2 advantages of tidal power

No CO2/greenhouse gases emitted, tidal power is renewable, once built tidal barrages last a long time.

Give 2 disadvantages of tidal power

Expensive to construct, only suitable for the mouths of tidal rivers so not everywhere, environmental impact of tidal barrages is unknown

Give 2 advantages of nuclear power

No CO2/greenhouse gases emitted. Large power produced for small mass of fuel, reliable output as it is not affected by weather, fuel will last for a long time, fuel has a high energy density

Give 2 disadvantages of nuclear power

Nuclear waste is radioactive and needs to be stored carefully, there is risk of an accident such as Chernobyl, expensive to build power station, takes a long time to build a power station, expensive and difficult decomission at the end of the power station's life.

What are the energy transfers for an object that is falling?

GPE to kinetic energy via work done via gravity.

State the equation for effiency

Efficiency = useful energy / energy input OR useful power / power input

Describe the energy transfers in coal power station.

Chemical store in fuel, heat transfer to thermal store of steam which does work on the turbines to turn them (kinetic store) which turns the generator which transfers electrical energy to the national grid.

How can insulation be improved?

Increase thickness of insulator, make the inside surface of the insulator reflective, put an airgap between layers of insulation

What is a Watt?

1 joule of energy transferred per second

A tennis ball is thrown at the ground, why will it bounce up to higher than it was dropped?

At the start the ball has kinetic and gravitational potential energy. Energy is conserved so at the end the initial kinetic energy is converted to GPE allowing the ball to reach higher

Describe radiation

All objects emit infra red radiation which is energy transferred as a wave. Radiation can travel through a vacuum. It is more easily absorbed and emitted by matte black surfaces than shiny silver ones.

What are the energy transfers for a moving object hitting an obstacle?

Kinetic energy to thermal store of object and surroundings via heating

Explain why a metal is a better conductor than a non-metal

A metal has delocalised electrons which are free to move through the material. These electrons move quickly and collide with metal ions throughout the metal transferring energy to the particles.

How is energy often dissapated?

Heat loss to the surroundings, Work done against air resistance, Work done against friction.

Give the 8 stores of energy required for GCSE

Magnetic, Thermal, Chemical, Kinetic, Electrostatic, Elastic potential, Gravitational potential, Nuclear

Describe and experiment to measure the kinetic energy gained by rolling a trolley down a ramp.

Measure the mass of the trolley using a mass balance. Put an interrupt card on the trolley and measure the length using a metre rule, input this value to the data logger. Roll the trolley down a ramp so that it passes through a light gate connected to a data logger at the end. The light gate will calculate speed = length of interrupt card/time the light beam is blocked. Then use this in the equation KE = 1/2mv^2

Describe an experiment to measure the gravitational potential energy gained by an object as it is lifted by a motor

Measure the mass of the object with a mass balance. Measure the change in height with a ruler. Measure the inital and final heights reached using the bottom of an object as a reference point. Clamp the ruler and use a set square to ensure the ruler is upright. Calculate the gpe by using the equation gpe = mg (change in h)

Explain what practical measures can be taken to imporve the effiency of a machine

You can lubricate joints and gears, tighten bolts etc. to minimise vibrations, thicker electrical cables for electrics.

What are the energy transfers for a vehicle slowing down

Kinetic energy to thermal store of the brakes and surroundings (via frictional force)

Explain what is meant by the conservation of energy?

Energy cannot be created or destroyed, it is just transferred between different energy stores

What are the energy transfers for an object being accelerated bya constant force

Mechanical (work done by force) to kinetic energy

What are the effects of the thickness and thermal conductivity of the walls of a building on its rate of cooling?

Cooling is faster if walls are thinner and have a higher thermal conductivity

What is meant by energy dissipating?

Energy spreads out and becoming less useful (usually when energy is transferred to the surroundings)

Describe Convection

The fluid closest to the heat source is heated and becomes hotter and takes up more volume so is less dense. This hot fluid rises and is replaced by cooler denser fluid which is then heated and the process continues.

What are the energy transfers for bringing water to a boil in an electric kettle?

Electrical working to thermal store of water (and thermal store of surroundings and kettle)

A tennis ball is dropped, why will it not bounce above the point it was released.

Energy is conserved, the GPE at the end cannot be more than at the start so will not reach a higher height

You will need to know about the following energy resouces: fossil fuels, nuclear fuel, bio-fuel, wind, hydroelectricty, the tides and the Sun. Sort these into renewable and non-renewable

Renewable - Bio-fuel, wind, hydroelectricity, tidal, solar; Non-renewable - fossil fuels, nuclear

You will need to know about the following energy resouces: fossil fuels, nuclear fuel, bio-fuel, wind, hydroelectricty, the tides and the Sun. Sort these into those that produce a predictable output and those that don't.

Predictable output - fossil fuels, nuclear, bio-fuel, hydroelectricity, tidal; Not predictable - solar and wind

Give the energy transfers required for GCSE.

Mechanical work, Electrical work, Heating, Radiation

What are the energy transfers for an object projected upwards or up a slope?

Kinetic energy -> GPE via work done against gravity

A tennis ball is dropped, why will not bounce up to the point it was released.

Energy is dissapated to the thermal store of the surroundings due to work done against air resistance so the gpe of the ball be less than at the start

Describe conduction

Particles gain energy and vibrate more these collide with neighbouring particles which pass the heat energy along

What is meant by power?

Rate of energy transferred. Measured in Watts.