Energy

Question 1

Name 5 ways you can reduce energy loss in your home.

Answer 1

Choose from:

• loft insulation,
• cavity wall insulation,
• double glazing,
• draught excluders,
• silver foil behind radiators.
• carpet, rugs and underlay

Question 2

Give 2 advantages of using fossil fuels to make electricity.

Answer 2

Advantage 1. Fossil fuels are readily available. Advantage 2. Gas power stations have a short start up time meaning the power station can quickly respond to an increased demand.

Question 3

Name 4 energy resources that are renewable.

Answer 3

Chosse 4 energy resources that are renewable

from biofuel,

wind,

hydro-electricity,

geothermal,

the tides,

the Sun

and water waves.

Question 4

A crane does 15,000J of work in 30 seconds. What is its power?

Answer 4

Power = work done/time taken

=15,000/30

= 500W

Question 5

Give 2 advantages of using renewable sources to make electricity

Answer 5

This will depend on the renewable source used but in general:

Advantage 1. No carbon dioxide is released so the production of energy does not add to climate change. Advantage 2. renewable sources are or can be continuously replaced and so will never run out.

Question 6

What will affect how fast a building loses heat energy?

Answer 6

The rate of cooling of a building
is affected by the thickness and thermal conductivity of its walls.

Question 7

Heat energy only flows in which direction?

Answer 7

From hotter objects to colder objects.

Question 8

What is the equation to find gravitational potential energy?

Answer 8

Question 9

Would you want a high or low specific heat capacity for a liquid used to fill a radiator? Why?

Answer 9

You would want a high specific heat capacity for a liquid used to fill a radiator because it would store a lot of energy and cool down slowly.

Question 10

What is specific heat capacity?

Answer 10

The energy needed to raise the temperature of 1 kg of a substance by 1 degree.

Question 11

What is power measured in?

Answer 11

Power is measured in Watts.

1 Watt = 1 Joule per second.

Question 12

What is a renewable energy resource?

Answer 12

A renewable energy resource is one that is being

(or can be) replenished as it is used

Question 13

What is meant by Power?

Answer 13

Power is a measurement of how quickly work is done. The faster you do work, or transfer energy, the greater your power.

Question 14

If a substance has a high specific heat capacity, what does this tell you about the amount of energy it stores?

Answer 14

Substances with a high specific heat capacity take a lot of energy to heat up, so can store a lot of energy.

Question 15

What is meant by Work Done?

Answer 15

Work Done is the energy transferred when a force acts over a certain distance.

Question 16

What does thermal conductivity mean?

Answer 16

The higher the thermal conductivity of a material the higher the rate of
energy transfer by conduction across the material.

Question 17

If a substance has a high specific heat capacity, what does this tell you about how it heats up?

Answer 17

Substances with a high specific heat capacity take a lot of energy to heat up, so will heat up slowly.

Question 18

Describe the energy change of an object accelerated by a constant force

Answer 18

The object will gain speed and so gains kinetic energy.

Question 19

A car has a mass of 1000kg and a speed of 10m/s. What is its kinetic energy?

Answer 19

KE = 1/2 mv²

KE = 1/2 x 1000 x 10²

= 50,000J

Question 20

Describe the energy changes in a vehicle slowing down

Answer 20

As the vehicle slows down it loses kinetic energy. This is converted into heat due to friction with the air and the brake blocks and the tyres.

Question 21

You will be given the equation to calculate the energy in a coiled spring. Can you rearrange this to find the spring constant?

Answer 21

The spring constant k =E/ 0.5 x e²

Question 22

Name 4 energy resources that are non-renewable.

Answer 22

Oil, coal, gas and nuclear fuels such as Uranium are all non-renewable.

Question 23

What is meant by ‘efficiency’?

Answer 23

A measurement of the useful energy output as a percentage of the total energy input.

Eg. a light bulb that converts 50 J of energy into light out of 200 J of electricity supplied would be 25% efficient.

Question 24

If a substance has a high specific heat capacity, what does this tell you about how it cools down?

Answer 24

Substances with a high specific heat capacity store a lot of energy so will cool down slowly.

Question 25

Describe the energy changes when a moving object hits an obstacle

Answer 25

The moving object has Kinetic Energy. When it hits an obstacl it loses this KE (and comes to a sudden stop). The energy is converted into sound, possibly light and heat energy and possible some KE if the obstacle moves.

Question 26

Rearrange: work done = force x distance so that it is:force =

Answer 26

You should get: force = work done/distance.

Question 27

Give 2 advantages of using nuclear fuels to make electricity

Answer 27

Nuclear fuels such as Uranium and Plutonium release energy without being burned. Advantage 1. Nuclear fuel releases a lot more energy per kg than a fossil fuel. Advantage 2. As nuclear fuel does not need to be burnt to release energy it does not release CO2 and add to climate change.

Question 28

Give 2 disadvantages of using nuclear fuels to make electricity

Answer 28

Nuclear fuels such as Uranium and Plutonium release energy without being burnt. Disadvantage 1. Nuclear fuel produces nuclear waste which remains radiaoactive for 1000's of years. This waste is a cancer risk and needs to be strored safely away from people. Disadvantage 2. Nuclear power stations are expensive to build and decomission (break up at the end of their life).

Question 29

Describe the energy changes when an object is projected upwards

Answer 29

At the start of its journey the object, lets imagine that it's a ball, will be going the fastest it will travel (it has maximum KE). As it gets higher it slows down (loses KE) This kinetic energy is converted to GPE, the ability to fall. At the top of its arc the ball has maximum GPE but zero KE. The ball then starts to fall to earth, gaining speed and KE but losing GPE.

Question 30

What happens to kinetic energy if: (a) the mass is doubled? (b) the speed is doubled?

Answer 30

KE = 1/2 mv2 so (a) KE doubles (b) KE quadruples

Question 31

Give 2 disadvantages of using renewable sources to make electricity

Answer 31

This will depend on the renewable source used but in general: Disadvantage 1. Renewable sources are ugly, we call this visual pollution. Disadvantage 2. Renewable sources have a negative effect on wildlife.

Question 32

When do things cool down the fastest?

Answer 32

When there is a big difference in temperature.

Question 33

Give 2 disadvantages of using fossil fuels to make electricity

Answer 33

Fossil fuels include coal, oi and gas and petrol and diesel which are made from oil. Disadvantage 1. Burning fossil fuels releases harmful gases such as CO2 which increases climate change. Disadvantage 2. Fossil fuels are non-renewable and are expected to run out this century.

Question 34

Describe all the changes involved in the way energy is stored when an electric kettle boils water.

Answer 34

The kettle uses elelctrical energy and turns it into heat energy which is passed to the water. As the water boils the water particles gain KE. You would lose energy in heating the kettle itself and the surroundings- also some energy as noise and in the light that shows the kettle is on.

Question 35

Give 2 disadvantages of using biomass (a renewable source) to make electricity

Answer 35

Biomass fuels such as wood, oils and alcohol have to be burnt to release energy. Disadvantage 1. Biomass is only a renewable resource if plants are replanted. It has lead to deforestation in Asia and the Amazon. Disadvantage 2. When burned, biomass gives off CO₂ which increases climate change. Disadvantage 3. Biomass fuels can be grown instead of food crops. (In theory this is the same mass of CO₂ given out that the plants used in photosynthesis. This is why biomass is called a carbon neutral source. In reality this doesn't balance.)

Question 36

What is a Sankey diagram?

Answer 36

A diagram that uses arrows to show energy transfer and efficiency.

Question 37

Give 2 advantages of using biomass (a renewable source) to make electricity

Answer 37

Biomass fuel has to be burnt to release energy. It is a large group of fuels including wood, oils from seeds, alcohol from plant sugars, poo, rubbish and any other organic matter Advantage 1. It is a cheap and readily available source of energy. Advantage 2. If replaced, biomass can be a long-term, sustainable energy source.