IB Physics SL B.1.2 Density

Practise calculating density, mass and volume in contexts from liquids to icebergs, with clear substitutions and correct units.

Exam points

calculate density from mass and volume, or rearrange ρ = m/V to find an unknown quantity with correct SI units
use geometry with density to show a mass, such as an iceberg, from dimensions inferred from floating-depth data
estimate atomic spacing by finding volume per atom from bulk density, then taking the cube root of that volume

[Maximum number: 2]

This question is about a tidal power station.

A tidal power station is built for a coastal town. Sea water is stored in a tidal basin behind a dam at high tide and released in a controlled manner between high tides, so that it passes through turbines to generate electricity.

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Table for Question B.1.2—Density question 1 — IB Physics SL

Show that the mass of sea water released between successive high and low tides is about $2.8 \times 10^{8} \mathrm{~kg}$ .

$m=\rho \Delta V=\rho A \Delta h$ ;

\begin{aligned} & =1.1 \times 10^{3} \times 1.4 \times 10^{5} \times 1.8 ; \\ & \left(\approx 2.8 \times 10^{8} \mathrm{~kg}\right) \end{aligned}

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B.1.2—Density question 1