Explain why the forces on the brick at the bottom of the pool cause the brick to be stationary. The forces acting on the brick include the gravitational force pulling it downward and the buoyant force pushing it upward. At the bottom of the pool, the weight of the brick is exactly balanced by the upward forces (normal force and buoyant force), resulting in a net force of zero. Therefore, according to Newton's first law, the brick remains stationary as the forces are in equilibrium.

GCSE AQA Physics Pressure & Pressure Differences in Fluids: Explain why the forces on the br

Explain why the forces on the brick at the bottom of the pool cause the brick to be stationary - AQA - GCSE Physics - Question 8 - 2022 - Paper 1

Question 8

Explain why the forces on the brick at the bottom of the pool cause the brick to be stationary. The forces acting on the brick include the gravitational force pulli... show full transcript

Worked Solution & Example Answer:Explain why the forces on the brick at the bottom of the pool cause the brick to be stationary - AQA - GCSE Physics - Question 8 - 2022 - Paper 1

Step 1

08.2 - Calculate the density of the water in the swimming pool.

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Answer

To calculate the density of the water, we will use the formula relating pressure (P), area (A), and hydrostatic force:

Calculate the Area (A): Given the dimensions of the brick,

$A = 0.25 m \times 0.10 m = 0.025 m^2$
Use the Pressure Formula (P = F/A): Here, the force (F) is the weight of the water acting on the top surface:

$P = \frac{F}{A} = \frac{637 N}{0.025 m^2} = 25,480 Pa$
Calculate the Density (\rho): Using the hydrostatic pressure formula:

$P = \rho g h$ Where:
- $g = 9.8 \frac{N}{kg}$ (gravitational field strength)
- $h = 2.5 m$ (depth of water above the brick)
Rearranging gives: $\rho = \frac{P}{gh} = \frac{25480 Pa}{9.8 \frac{N}{kg} \times 2.5 m} \approx 1040 \frac{kg}{m^3}$

Therefore, the density of the water in the swimming pool is approximately 1040 kg/m³.

Step 2

08.3 - Determine the force due to the weight of the water on the top surface of the brick in Figure 15.

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Answer

To find the force acting on the brick at a depth of 2.50 m in the deep swimming pool:

Calculate the Pressure at 2.50 m Depth: Using the formula:

$P = \rho g h$ Substituting the values we calculated earlier:

$P = 1040 \frac{kg}{m^3} \times 9.8 \frac{N}{kg} \times 2.5 m \approx 25,480 Pa$
Calculate the Force (F): Using the area calculated previously:

$F = P \times A \approx 25,480 Pa \times 0.025 m^2 \approx 637 N$ However, the force from the question indicates the new scenario in the deep pool:

Given the new force: $F = 618 N$ (as given in the problem)

Therefore, the force due to the weight of the water on the brick in Figure 15 is 618 N.

Explain why the forces on the brick at the bottom of the pool cause the brick to be stationary - AQA - GCSE Physics - Question 8 - 2022 - Paper 1

Worked Solution & Example Answer:Explain why the forces on the brick at the bottom of the pool cause the brick to be stationary - AQA - GCSE Physics - Question 8 - 2022 - Paper 1

08.2 - Calculate the density of the water in the swimming pool.

08.3 - Determine the force due to the weight of the water on the top surface of the brick in Figure 15.

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