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

To find the mean pressure, we first calculate the average of the pressures given:

ext{Mean Pressure} = rac{0.115 + 0.120 + 0.121 + 0.116}{4} = 0.118 MPa

Next, we determine the range of the pressures:

$ext{Range} = 0.121 - 0.115 = 0.006 MPa$

The uncertainty is half of the range:

ext{Uncertainty} = rac{0.006}{2} = 0.003 MPa

Thus, the uncertainty in the mean pressure is ± 0.003 MPa.

The relationship is linear, which means that pressure increases at a consistent rate as temperature rises. This relationship can be described with the equation $P = mT + c$, where $P$ is pressure, $T$ is temperature, $m$ is the slope of the graph, and $c$ is the y-intercept. As temperature increases, the average kinetic energy of the gas particles increases, causing more frequent and forceful collisions with the walls of the container, which in turn increases the pressure.

As the water in the pressure cooker boils, the amount of steam increases, resulting in more gas particles in the container. Additionally, the temperature of the steam rises above 100 °C. With the increase in steam and temperature, the kinetic energy of the particles increases, leading to more frequent collisions with the walls of the cooker. This increase in collision frequency and force raises the pressure inside the cooker.

When steam is released through the safety valve, the particles of steam move from a confined space to a larger volume in the atmosphere. As the steam expands, it occupies more space, which results in a decrease in the number of particles per unit volume. Consequently, the density of the steam decreases because density is defined as mass per unit volume. Thus, as the steam disperses, the arrangement of particles becomes less dense, leading to a lower density of the steam.