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Figure 7 shows cavity wall insulation being installed in the wall of a house - AQA - GCSE Physics Combined Science - Question 5 - 2018 - Paper 1
Question 5
Figure 7 shows cavity wall insulation being installed in the wall of a house. 05.1 Explain how the wall reduces unwanted energy transfers. 05.2 The cavity insula... show full transcript
Worked Solution & Example Answer:Figure 7 shows cavity wall insulation being installed in the wall of a house - AQA - GCSE Physics Combined Science - Question 5 - 2018 - Paper 1
Step 1
05.1 Explain how the wall reduces unwanted energy transfers.
Answer
The wall consists of two or three layers, including cavity wall insulation, brick, and block. This structure effectively reduces unwanted energy transfers due to the following reasons:
- Layer Composition: The wall is thick, which provides additional resistance to heat transfer.
- Low Thermal Conductivity: Cavity wall insulation materials are specifically designed to have low thermal conductivity, meaning they allow less heat to pass through compared to standard building materials. This significantly reduces the amount of energy lost through conduction.
Step 2
05.2 Determine the temperature inside the house after 30 minutes.
Answer
To find the temperature after 30 minutes, we can observe the values from Table 4. At 20 minutes, the temperature was 20.8 °C, and at 40 minutes, it was 17.4 °C. We can calculate the midpoint temperature at 30 minutes using linear interpolation:
ext{Temperature at 30 min} = rac{20.8 + 17.4}{2} = 19.1 ext{ °C}
Step 3
05.3 Describe how different energy stores are changed by the boiler.
Answer
The gas boiler affects various energy stores as follows:
- Chemical Energy: The chemical energy of the fuel decreases as it is burned to produce heat.
- Thermal Energy: The thermal energy store of the water increases as it absorbs heat from the hot gases, resulting in hot water.
- Kinetic Energy: The kinetic energy of the air particles can also increase as warm air is circulated.
Step 4