A student investigated how the pressure of a gas depends on its temperature - AQA - GCSE Physics Combined Science - Question 4 - 2022 - Paper 1

To calculate the uncertainty in the mean pressure, we first determine the range of the pressure readings from the table:

• Highest Pressure: 0.121 MPa
• Lowest Pressure: 0.115 MPa

The range is given by:

$\text{Range} = 0.121 - 0.115 = 0.006 \text{ MPa}.$

The uncertainty is half of the range:

$\text{Uncertainty} = \frac{0.006}{2} = 0.003 \text{ MPa}.$

The relationship between temperature and pressure is linear, which means that as one variable increases, the other also increases at a constant rate. This can be expressed using the linear equation format:

$P = mT + c$

where P represents pressure, T represents temperature, m is a constant (the gradient of the graph), and c is the y-intercept.

As the amount of steam in the pressure cooker increases, the number of particles also increases, which results in more frequent collisions with the walls of the cooker. Additionally, as the temperature increases, the particles gain kinetic energy, moving faster and colliding more forcefully with the walls. This increase in particle collisions raises the overall pressure within the cooker.

When steam is released through the safety valve, it expands as it moves into the atmosphere. Consequently, the particles spread out, leading to a decrease in density because density is defined as mass per unit volume. As the steam occupies a greater volume in the atmosphere, its density decreases, which can be represented mathematically as:

$\text{Density} = \frac{\text{mass}}{\text{volume}}.$