Syllabus 1.3–1.4 · Mass, weight & density
Same matter.
Different effects.
Keep mass distinct from weight, measure density from reliable evidence and use density to predict floating, sinking and liquid layering.
Part A · Mass & weight
Investigation 1
Move the same object through different fields
Mass measures quantity of matter in an object at rest relative to the observer. Weight is the gravitational force on that mass.
Earth · 9.8 N/kg
Part A · Mass & weight
Investigation 2
Measure gravitational field strength and compare masses
Use g = W/m, connect N/kg to free-fall acceleration, and compare mass with a beam balance.
Newton meter experiment
g = W ÷ m = 39.2 ÷ 4 = 9.8 N/kg
Numerically, gravitational field strength in N/kg equals acceleration of free fall in m/s².
Beam balance
balanced: masses are equal
A beam balance compares weights on the same world; the common value of g cancels, so it compares masses.
Part B · Density
Investigation 3
Determine the density of a liquid
Measure the empty cylinder, measure cylinder plus liquid, subtract, then divide liquid mass by volume.
Part B · Density
Investigation 4
Determine solid density
Find volume from dimensions for a regular solid or from liquid displacement for an irregular solid that sinks.
Part B · Density
Investigation 5
Predict floating from density data
Compare object density with liquid density before revealing the observation.
Part B · Density · Supplement
Investigation 6
Build a column of non-mixing liquids
Predict which liquid floats on another from density data, assuming the liquids do not mix.
Assessment
Check all Mass, Weight & Density objectives
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