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Figure 23 shows some water in a tank - Edexcel - GCSE Physics - Question 10 - 2021 - Paper 1
Question 10
Figure 23 shows some water in a tank. (i) The bottom of the tank has an area of 0.80 m². The force on the bottom of the tank, due to the water, is 2400 N. Calculate... show full transcript
Worked Solution & Example Answer:Figure 23 shows some water in a tank - Edexcel - GCSE Physics - Question 10 - 2021 - Paper 1
Step 1
Calculate the pressure, due to the water, on the bottom of the tank.
Answer
To calculate the pressure, we use the formula:
ext{Pressure} = rac{ ext{Force}}{ ext{Area}}Given that the force on the bottom of the tank is 2400 N and the area is 0.80 m², we can substitute these values into the formula:
ext{Pressure} = rac{2400 ext{ N}}{0.80 ext{ m}²} = 3000 ext{ Pa}Thus, the pressure on the bottom of the tank is 3000 Pa.
Step 2
Explain how the pressure on the bottom of the tank changes when more water is added to the tank.
Answer
When more water is added to the tank, the height of the water column increases. The pressure at the bottom of the tank is directly proportional to the height of the water column according to the formula:
where:
- density is the density of water,
- g is the acceleration due to gravity,
- h is the height of the water column.
As height (h) increases, the pressure on the bottom of the tank increases.
Step 3
Use the graph to find the change in atmospheric pressure as the aeroplane descends.
Answer
From the graph in Figure 25, at 6000 m, the atmospheric pressure is approximately 40 kPa, and at 2000 m, it is about 80 kPa. Thus, we calculate the change in pressure as follows:
Therefore, the change in atmospheric pressure as the aeroplane descends is 40 kPa.
Step 4
Suggest one reason why the atmospheric pressure is greater at 2000 m than at 6000 m.
Answer
The atmospheric pressure is greater at 2000 m than at 6000 m because pressure decreases with increasing altitude due to the decreasing weight of the air overhead. At higher altitudes, there are fewer air molecules above, resulting in lower pressure.
Step 5
Explain why the person exerts a different pressure on the bed when standing up than when lying down.
Answer
When a person stands up, their weight is concentrated over a smaller surface area (the feet), resulting in higher pressure on the bed. Conversely, when lying down, the weight is distributed across a larger surface area (the back), leading to lower pressure on the bed. Pressure is defined as force per unit area, thus:
ext{Pressure} = rac{ ext{Weight}}{ ext{Contact Area}}