A Levels Physics (9702)•9702/13/O/N/22

Explanation
Pressure equals weight divided by contact area Steps:
- Weight of cube W = mass m × g, where g is acceleration due to free fall.
- Mass m = density ρ × volume V, and for cube V = s³ with side length s.
- Contact area A = s² (face area).
- Pressure P = W / A = (ρ × s³ × g) / s² = ρ × g × s.
Why C is correct:
- Pressure on the base equals ρ g h from hydrostatics, where h = s (side length) is the height of the cube.
Why the others are wrong:
- A: Product ρ g has dimensions of pressure per length, omitting size factor; pressure increases with cube size.
- B: Product ρ g A has dimensions of mass per time squared, not pressure; area appears in denominator of formula.
- D: Product ρ g V equals weight (force), not pressure; lacks division by area.
Final answer: C
Topic: Density and pressure
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