Density Calculations (GCSE Physics)
Density Calculations
Practice Questions
Question: Finola has a brick with volume 146cmÂł and mass 4,500g. Calculate the density of the brick with correct units, to 1 dp.
1. Write out the equation.
⍴ = m / v
2. Convert the units. In the question, we have been given the mass in grams, but to use the equation we need a mass in kilograms. Similarly, we have been given the volume in cmÂł, so we need to convert into mÂł.
Since 1000g = 1 kg
4500 grams = 4.5 kg
Since 1,000,000 cmÂł = 1mÂł
146 cmÂł = 0.000146 mÂł
3. Substitute in the numbers.
Now that we have the mass in kilograms, we can use the equation. We need to remember to give our answer to 1dp and state the correct units.
⍴ = 4.5 / 0.000146
⍴ = 30821.91781
⍴ = 30821.9 kg/m³
Question: A bottle of juice has a mass of 0.6kg and density of 1100 kg/ mÂł. Calculate the volume of the water bottle, giving your answer in litres to 1 dp.
1. Write out the equation.
⍴ = m / v
2. Rearrange the equation. We want to calculate the volume, v.
⍴ = m / v
v = m / ⍴
3. Substitute in the numbers.
v = 0.6 / 1100
v = 0.0005454…
v = 0.0005mÂł
4. Convert the units. The questions asks for the answer in litres, so must convert from mÂł.
v = 0.0005mÂł
0.0005 x 1000 = 0.5L
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