Question 153128
If 1.0 km cubed of air has mass 1,200,000,000 kg, what is the density of air in g/cm cubed? The answer is given as 1.2x10 to the negative 3 g/cm cubed.
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Comment: The key is to properly change (km)^3 to (cm)#.
(km)^3 = (1000m)^3 = (1000*100cm)^3 = (10^5cm)^3 = 10^15cm^3
(1.2x10^9 kg/1.0 km^3)(1000g/1kg)[(km)^3/(10^15cm^3)]
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Cancel the units to get g/cm^3
Evaluate the quantities as follows:
[1.2x10^9 * 1000 * 1] / [1.0 * 1 * 10^15] = [1.2*10^12]/[10*15] = 1.2x10^-3
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Final answer 1.2x10^-3 g/cm^3
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Cheers,
Stan H.