DENSITY AND PRESSURE
4 marks · NormalA rectangular metal bar has a length of 0.20 m, a width of 0.06 m, and a height of 0.04 m. Its mass is 0.86 kg.
Calculate the volume of the metal bar. Give your answer in m³.
Calculate the density of the bar. Give your answer to 2 significant figures and state the unit.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) 4.8 × 10⁻⁴ m³
(b) 1.8 × 10³ kg/m³
Common mistakes: Inconsistent units; Wrong significant figures
Show mark scheme and worked solution
Marking points
M1 (a) · 1 mark · Multiplies length × width × height to find volume
A1 (a) · 1 mark · Writes the result in m³ (4.8 × 10⁻⁴ m³ or 0.00048 m³)
M2 (b) · 1 mark · Substitutes mass and (their) calculated volume into p = m/V (follow-through)
A2 (b) · 1 mark · Answer to 2 significant figures with unit kg/m³ (1.8 × 10³ kg/m³)
Worked solution
(a) Volume = length × width × height = 0.20 × 0.06 × 0.04 = 0.00048 m³
(b) p = m / V = 0.86 / 0.00048 ≈ 1791.67 ≈ 1.8 × 10³ kg/m³ (to 2 significant figures)