Figure 7 shows cavity wall insulation being installed in the wall of a house - AQA - GCSE Physics Combined Science - Question 5 - 2018 - Paper 1

To find the temperature after 30 minutes, we can calculate the average temperature of the intervals surrounding the 30-minute mark:

Using the values from the table:

• At 20 minutes, the temperature is 20.8 °C.
• At 40 minutes, the temperature is 17.4 °C.

Using the formula for the average:

T = \frac{T_{20} + T_{40}}{2} = \frac{20.8 + 17.4}{2} = 19.1 \, ^{\circ}C

So, the temperature inside the house after 30 minutes is approximately 19.1 °C.

The gas boiler alters various energy stores in the following ways:

1. The chemical energy store of the fuel decreases as it is burned to produce heat.
2. The thermal energy store of the water increases as it absorbs heat from the hot gases, raising its temperature.
3. The thermal energy store of the air or atmosphere increases, as heat is released into the surrounding environment.

To find the power of the boiler, we can use the equation:

$P = \frac{E}{t}$

Where:

• $E = 15 \, MJ = 15,000,000 \, J$
• $t = 10 \, minutes = 10 \times 60 = 600 \, seconds$

Now substituting the values in:

$P = \frac{15,000,000 \, J}{600 \, s} = 25,000 \, W$

Thus, the power of the boiler is 25,000 W.