PHYSICS CONNECTION
Small length errors can matter greatly in density
Density depends on mass and volume. When volume is calculated from a diameter or side length cubed, its fractional uncertainty is amplified.
ρ = m/V For V ∝ d³: percentage uncertainty in V ≈ 3 × that in d
Follow the reasoning
- Write volume in terms of the measured dimensions.
- Apply the appropriate powers when combining uncertainties.
- Combine the mass and volume contributions for density.
OFFICIAL OCR QUESTIONS
Try it in a past paper 2
Open the question, then use its mark scheme to check your work.
Question 15
Combine mass and length uncertainties when calculating density.
Question 2
Use repeated diameter readings, density and upthrust to analyse a floating cylinder.
A curated collection checked against the question papers and mark schemes; not a complete past-paper catalogue. Links open official OCR PDFs in a new tab.
ORIGINAL PHYSICSUK QUESTIONS
Put the ideas to work
More practice is on its way
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Specification outcomes (2)
- 3.2.4(a) Define density; ρ = m / V.
- 2.2.1(c) Calculate absolute and percentage uncertainties when data are combined by addition, subtraction, multiplication, division or raising to powers.