Making Use of Energy (WJEC GCSE Science (Double Award): Physics): Exam Questions

The diagrams below show the apparatus used to find the density of a fragment of bone.

The diagram of the measuring cylinder shows the water level before and after the bone fragment was added.

(i) Use the information in the diagrams to complete the table below.

[2]

(ii) Use an equation to calculate the density of the bone fragment.

[2]

Density = .......... g/cm³

Explain, in terms of particles, why bone has a greater density than water.

About 30% of all the heat lost from an uninsulated house escapes through the walls.

Houses built in Wales since 1990 have wall insulation installed. One type of insulation that is commonly used is cavity board. This is a sheet of solid foam that is covered on both sides with shiny silver foil. During construction, sheets of cavity board are placed between the inner and outer walls of the house.

Explain why heat is lost through the walls of a house and how cavity board can reduce this heat loss by conduction, convection and radiation.

The table shows some information about three types of house with cavity board installed. All three houses use gas central heating.

(i) The payback time of installing cavity board in a semi-detached house is 3 years. A semi-detached house owner claims that she has a longer payback time than the owner of the mid-terraced house. Explain whether you agree with her statement.

[2]

(ii) Complete the table for the two missing values.

[2]

(iii) Use information in the table to explain which of the three types of house has the smallest impact on the environment.

[2]

A group of students investigated different methods of heat transfer.

First, they added a purple crystal to a beaker of water and heated it up as shown below.

(i) Circle the method of heat transfer that was being investigated.

[1]

(ii)

I. State what the students observed. You may add to the diagram if you wish.

[1]

II. Give a reason for your answer to part I.

[1]

In their next experiment the students placed 4 metal rods on a tripod.

The rods were identical except they were made from different metals.

They attached a drawing pin to the end of each rod with Vaseline.

They heated the other end of each of the rods and recorded the time for each pin to drop off.

The students recorded the following results:

List the metals in order from best conductor to worst conductor.

Best conductor: .......................................

.......................................

Worst conductor: .......................................

.......................................

The diagram shows a solar heating panel that is installed on a roof. The liquid in the solar panel becomes heated by radiation from the Sun. The heated liquid passes through coils of copper piping inside a heat exchanger resulting in water heating up.

Explain, in terms of particles, how heat energy conducts through the walls of the copper piping in the heat exchanger.

Explain why the liquid in the solar panel circulates in the direction shown.

In good sunlight, each square metre of the solar panel receives 960 J of energy per second from the Sun. Only of this energy is used to heat the liquid.

Calculate the amount of energy given to the liquid per second if the panel has an area of 2 m².

[2]

Energy given to the liquid per second = .......... J

Describe how the density of a small pebble, which is not a regular shape, can be determined.

Peter carries out an experiment to find the density of iron.

Stage 1

• He uses a balance to measure the mass of a piece of iron.

Stage 2

• He fills a displacement can with water.

• He waits until water stops flowing from the spout.

• He then places an empty measuring cylinder under the spout.

Stage 3

• He carefully lowers the iron into the water.

• He collects the water displaced in the measuring cylinder.

Use information from the diagrams to answer the following questions.

(i) State the mass of the iron.

[1]

mass = .......... g

(ii) State the volume of the iron.

[1]

volume = .......... cm³

(iii) I. Use the equation:

to calculate the density of iron.

[2]

density = ..........

II. Underline the correct unit that should be used for the density above.

[1]

(iv) State one change to the apparatus that would improve the accuracy of the measurement of the mass of the iron.

[1]

A North Wales cheese producer checks the quality of their cheese by measuring its density. This can be carried out experimentally. The two diagrams show measurements that were carried out on a cube of cheese. The balance read 0.0 g before the cube of cheese was placed on it.

(i) Write down the mass of the cheese cube.

[1]

.......... g

(ii) Write down the length of one side of the cheese cube.

[1]

.......... cm

(iii) Use the equation:

volume of a cuboid = length × width × height

to calculate the volume of the cheese cube in cm³.

[1]

Volume = .......... cm³

(iv) Use the equation:

to calculate the density of the cheese cube and state the unit.

[3]

Density = .......... Unit = ..........

(i) A worker at the cheese factory suggests that the mass of the cheese cube should be measured more than once. State two reasons why this is good scientific practice.

[2]

(ii) State how the measurements could be improved.

[1]

The cube of cheese used in the experiment is now cut into two identical halves. One of these pieces is then cut in half. The sample of cheese has been divided into three pieces, one large piece and two identical small pieces.

Tick (✓) the two correct statements.

[2]

One of the small pieces of cheese is of the mass of the large piece.

One of the small pieces of cheese is of the volume of the large piece.

The three pieces of cheese have the same density.

The mass of the large piece of cheese is half the mass of the original cube.

The mass to volume ratio for each of the three samples is different.

All properties lose heat through their windows and roof. Energy-efficient installations such as uPVC windows and loft insulation keep homes warmer as well as reducing energy bills.

A homeowner replaces aluminium framed double glazed windows which contain metal spacers between the panes of glass with uPVC windows. This new frame is made of uPVC and the window panes are separated by non-metal spacers.

(i) Explain why the aluminium window loses heat at a faster rate than the new uPVC window. Include reference to particles in your answer.

[4]

(ii) The photograph shows an uninsulated loft.

Explain how heat is lost through the roof of a house when the loft is not insulated.

You should refer to the ceiling, the loft space and the roof tiles in your answer.

[3]

Explain why reducing energy losses from our homes benefits the environment.

A pupil sets up an experiment to investigate the absorption of heat radiation.

The diagram shows the apparatus set up before the heater was turned on for 8 minutes.

Two identical aluminium cans were both filled with 200 cm³ of water and a digital thermometer was inserted through a small hole in the lid.

One can was painted black and the other painted silver.

In the experiment several variables were controlled in order to make a valid conclusion.

Use the information above to describe how this was achieved.

In your answer include:

• three variables that were controlled

• an explanation of why each was controlled.

Each minute, the temperature of the water in each can was measured.

The data for the silver can have been plotted on the grid below and its best-fit curve drawn.

Apart from one result, the data points for the black can were also plotted on the grid.

(i) At 5 minutes the water temperature in the black can was 25 °C.

Plot this missing data point on the grid above and add the line of best fit.

[2]

(ii) Compare the temperature rise in the black can with the temperature rise in the silver can.

Explain your answer in terms of heat radiation.

[2]

A householder decides to replace his single glazed, aluminium framed windows. A company recommends fitting 'Energy Windows' like the one shown below.

Explain in terms of conduction, convection and radiation how the labelled features will help to reduce energy losses from the house. [6 QER]

A family fits double glazing to their house at a cost of £4 000. They save £80 per year on their heating bill.

(i) Calculate the payback time.

[1]

Payback time = .......... years

(ii) Suggest two reasons why this payback time may change.

[2]

A class carries out experiments to study heat transfer in solids and liquids.

In one experiment, the process of convection is shown by colouring some water with potassium permanganate(VII) crystals in the bottom corner of a beaker. The water is then heated and a clockwise convection current is set up.

Explain why the coloured water moves in the way described above.

In another experiment, four metal rods are tested to compare their ability to conduct heat energy.

The outcome of the experiment is as follows:

copper (best conductor)

aluminium

brass

iron (poorest conductor)

Explain in detail, the process of conduction in copper in terms of the motion of particles.

Describe how you would find the density of a small irregular-shaped rock.

You may assume that all the usual laboratory apparatus is available for you to use.

Include in your answer:

• the apparatus you would use

• a description of the method you would use to obtain results

• how the density would be calculated.

Joanne moves into an old house and has up to £1500 to spend on improving the insulation.

She finds the following information about different types of insulation.

Explain which two types of insulation she should fit to her house.

Include in your answer:

• The advantages of insulating the house

• The two types of insulation she should fit

• The reasons why she should choose these two types of insulation.