Physical Quantities & Measurements

What this chapter covers

1. Density

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   • Concept and UnitsMass per unit volume; kg/m³.
   • Density of a Regular SolidMass from balance, volume from dimensions.
   • Vessels for Measuring VolumeMeasuring cylinders and measuring beakers.
   • Density of an Irregular SolidVolume found by water displacement.
   • Density of a LiquidMass of known liquid volume.

2. Density Bottle

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   • Construction and PrincipleNarrow-necked bottle with holed stopper.
   • Density of a Liquid Using Density BottleThree weighings give liquid's density.

3. Relative Density

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   • Concept and UnitsRatio to water's density; no unit.
   • Measurement of Relative DensitySame three density-bottle readings used.

4. Density in Different States

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   • States ComparisonSolids generally densest, gases least dense.
   • Density DataCork 0.25 to mercury 13.6 g/cm³.

5. Floating and Sinking

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   • Floating and SinkingLess dense than liquid floats.
   • Principle of FloatationWeight versus buoyant force decides.
   • Law of FloatationFloating body displaces its own weight.

6. Applications of Floatation

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   • Iron ShipHollow volume lowers average density.
   • SubmarineFilling, emptying tanks sinks or raises.
   • Floatation of ManEasier to swim in sea water.
   • IcebergsIce floats about nine-tenths submerged.
   • FishesSwim bladder changes average density.
   • BalloonsHydrogen or helium makes them rise.

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