Changes of State & the Particle Model (AQA GCSE Physics: Combined Science)

Figure 1 below shows a wind turbine.

Figure 1

At a particular wind speed, a volume of 1.9 × 10⁴ m³ of air passes the blades each second.

The density of air is 1.2 kg/m³.

Calculate the mass of air passing the blades per second.

A student wants to calculate the density of the two objects shown in Figure 2 below.

Figure 2

Describe how the student could measure the densities of the two objects.

Kinetic theory states that all matter is made up of tiny particles, which are always moving.

The liquid shown in Figure 3 is evaporating.

Figure 3

Explain how the diagram in Figure 3 shows the liquid is evaporating.

Figure 4 shows the arrangement of particles in a solid.

Figure 4

The volume of one kilogram of solid is much smaller than the volume of one kilogram of gas.

Use the kinetic theory to explain why.

A student finds a small rock that she suspects is a meteorite. 

Measuring the density of the rock will give one piece of evidence to support her idea.

The volume of the piece of rock was 120.0 cm³.

The student measured the mass of the piece of rock as 895 g.

Calculate the density of the rock in g / cm³.

The graph in Figure 5 below shows the densities of some common types of rock.

Figure 5

Which type of rock most closely matches the rock the student measured?

Give one error that the student could have made when measuring the volume of the rock.

What effect would the error you described in part 4(e) have on the value of the volume of the rock that the student measured?

Figure 6 below shows a party balloon, filled with air.

Figure 6

State the name given to the sum of the potential and kinetic energy of all the particles of air inside the balloon.

State the equation which links mass, density and volume.

The balloon has a volume of 0.0283 m³.

The air in the balloon has a mass of 0.0340 kg.

Calculate the density of air.

The balloon is placed into very cold liquid nitrogen, causing the air inside to turn to a liquid.

During this process no air leaves the balloon.

State the name of the physical process which has taken place inside the balloon.

The air inside the balloon is now a liquid.

What is its mass?

Explain, in terms of particles, what has happened to the volume of the balloon.

Describe the arrangement of the particles in a solid, a liquid and a gas.

Describe the motion of the particles in a solid, a liquid and a gas.

During a dry day, a puddle on a road dries up and disappears.

State the name of the process which causes this to happen.

Describe one change in the weather that would cause the puddle to dry up more quickly.

A student takes an empty measuring cylinder and places it on an electronic balance.

She records the mass and then adds an unknown liquid to the measuring cylinder. She records the volume of liquid in the measuring cylinder and the reading on the electronic balance.

She repeats this process and plots her results on a graph shown in Figure 1.

Figure 1

Determine the mass of the empty measuring cylinder.

Figure 2 shows four different liquids and their densities.

Figure 2

Use the data from the graph and your answer to part (a) to identify the liquid which the student used. 

The following data may be useful:

1 m³ = 1 × 10⁶ cm³

The student repeats the experiment with a liquid which has a lower density. The same measuring cylinder was used for both experiments.

Draw a line on the graph to show the results she would expect to obtain from this second liquid.

A student wishes to measure the density of glass.

The following equipment is available:

• a bag of marbles, all made from the same type of glass
• a balance
• a plastic measuring cylinder containing water

Describe how the student could find the density of the glass used for the marbles. Make at least one suggestion to improve accuracy.

The table in Figure 1 shows the student's results.

Figure 1

Calculate the density of the marbles. Give the unit. 

Suggest how the student can use their value of density to identify the type of glass.

Suggest why the student may still be unsure about the type of glass.

Table 1 gives some observations about the shape and size of ice, water and steam.

Table 1

Explain each of the observations in terms of the arrangement and motion of the particles.

Figure 2 shows some large solid concrete cubes. 

Figure 2

The mass of one of the concrete cubes is 1000 kg. 

State the weight of this concrete cube.

Give the unit. 

The density of this concrete cube is 2300 kg/m³. 

Calculate the volume of this concrete cube. 

The concrete cube is used in an experiment to look at shielding for nuclear reactors. It is subjected to high temperatures until it melts.

Describe what will happen to mass of the concrete as it melts.