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H. Numerical problems. 1. 80 cm of iron weighs 624 g. Calculate thedensity of iron.2. A stone piece weighs 225 g. Bydisplacement method, its volume was foundto be 75 cm". What is the density of thestone piece?3. The density of copper is 8.9 g/cmFind itsvalue in kg/mº4. A cuboidal object of side 15 cm weighs1.35 kg. Calculate its density in kg/mº. |
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Answer» 1.An 80cm cube has a VOLUME of V = 0.8^3 = 0.512m^3This is SAID to “weigh” 624g = 0.624kg (which is a mass, not a WEIGHT). But that would produce a density of ρ = m/V = 0.624kg/0.512m^3 = 1.219kg/m^3And while the calculation is correct, the answer is nonsense, since the density of iron is approximately 7870kg/m^3, and this calculation shows the density as 1.219kg/m^3 – which is close to the density of nitrogen gas!Following Philip Kloppers suggestion, IF the “80cm cube” meant 80cm^3, which would be 8x10^-5m^3, then the density would be calculated as:ρ = 0.624kg/8x10^-5m^3 = 7800kg/m^3 which is at least, close to reality.4.Mass (m) = 1.35 kgSide (a) = 15 cm = 0.15 mVolume of a cube = SIDE x side x side = 0.153 = 0.003375 cu. MDensity (ρ) = Mass (m) / Volume (V)=> ρ = 1.35/0.003375=> ρ = 400 Kg/m3Explanation: |
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