Physical ScienceGrade 6-8
Density Answer Key
Discover how density is calculated and why objects float or sink in different liquids.
Prior Knowledge Questions
Q1.What is density?
Answer
Density is the amount of mass in a given volume of a substance (Density = Mass ÷ Volume).
Q2.What are the units for density?
Answer
Density is typically measured in g/cm³ (grams per cubic centimeter) or g/mL.
Q3.Why does ice float on water?
Answer
Ice floats because it is less dense than liquid water (ice density ≈ 0.92 g/cm³; water density = 1.0 g/cm³).
Activity A – Calculating Density
Q1.An object has a mass of 50g and a volume of 25 cm³. What is its density?
Answer
Density = 50g ÷ 25 cm³ = 2 g/cm³.
Q2.Will an object with a density of 0.8 g/cm³ float or sink in water?
Answer
It will float because its density (0.8 g/cm³) is less than water's density (1.0 g/cm³).
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