A solid block in the shape of a cuboid measures 20 cm by 40 cm by 50 cm.
The block exerts a force of 240 newtons on a floor.
The block can be placed on the floor on any one of its faces.
Work out the difference between the greatest possible pressure and the least possible pressure on the floor.
Give your answer in N/m². [4]
pressure $= \dfrac{\text{force}}{\text{area}}$
- identifies the smallest or largest face: $20 \times 40$ (= 800 cm²) or $40 \times 50$ (= 2000 cm²), or 0.08 m² or 0.2 m²M1
- correct conversion of area to m² (e.g. $800 \div 10\,000$) or lengths converted to metres before multiplying (0.2, 0.4, 0.5)M1
- $240 \div 0.08$ (= 3000) and $240 \div 0.2$ (= 1200), or both pressures in N/cm² (0.3 and 0.12) with intention to subtractM1
- 1800 (N/m²); 0.18 (N/cm²) scores M1 M0 M1 A0A1
- Answer: 1800 N/m²
- Examiner tip: Converting cm² to m² means dividing by 10 000, not 100 — convert the lengths to metres first to avoid this.