Materials Problem Solving

This lesson brings together all the concepts from the materials topic into multi-step problems, experimental design questions, and material selection challenges. These are the types of questions that appear frequently in Edexcel A-level Physics papers and require you to combine several equations and concepts.

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Multi-Step Calculations

Combining Density and Pressure

Problem 1: A cylindrical storage tank is filled with oil of density 850 kg m⁻³ to a depth of 6.0 m. The tank has a flat circular base of diameter 3.0 m. Calculate (a) the pressure at the base due to the oil, and (b) the force exerted on the base by the oil.

(a) Pressure = ρgh = 850 × 9.81 × 6.0 = 50 031 Pa ≈ 50.0 kPa

(b) Area of base = πr² = π × (1.5)² = 7.069 m² Force = pressure × area = 50 031 × 7.069 = 353 700 N ≈ 354 kN

Note: This is the force due to the oil only. The total force on the base also includes the force from atmospheric pressure above the oil, but in most problems you are asked for the force due to the fluid column alone.

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