CIE AS Physics (9702) exams from 2022

Revision Notes

4.2.1 Density

Density

  • Density is the mass per unit volume of an object
    • Objects made from low-density materials typically have lower mass. For example, a balloon is less dense than a small bar of lead despite occupying a larger volume
  • The units of density depend on what units are used for mass and volume:
    • If the mass is measured in g and volume in cm3, then the density will be in g/cm3
    • If the mass is measured in kg and volume in m3, then the density will be in kg/m3

 

Density equation, downloadable AS & A Level Physics revision notes

Equation for density

 

Density comparison, downloadable AS & A Level Physics revision notes

Gases are less dense than a solid

 

  • The volume of an object may not always be given directly, but can be calculated with the appropriate equation depending on the object’s shape

Volume of shapes, downloadable AS & A Level Physics revision notes

Volumes of common 3D shapes

 

Worked example

Worked example - density, downloadable AS & A Level Physics revision notes

Exam Tip

  • When converting a larger unit to a smaller one, you multiply (×)
    • E.g. 125 m = 125 × 100 = 12 500 cm
  • When you convert a smaller unit to a larger one, you divide (÷)
    • E.g. 5 g = 5 / 1000 = 0.005 or 5 × 10-3 kg
  • When dealing with squared or cubic conversions, cube or square the conversion factor too
    • E.g. 1 mm3 = 1 / (1000)3 = 1 × 10-9 m3
    • E.g. 1 cm3 = 1 / (100)3 = 1 × 10-6 m3

Author: Ashika

Ashika graduated with a first-class Physics degree from Manchester University and, having worked as a software engineer, focused on Physics education, creating engaging content to help students across all levels. Now an experienced GCSE and A Level Physics and Maths tutor, Ashika helps to grow and improve our Physics resources.
Close

Join Save My Exams

Download all our Revision Notes as PDFs

Try a Free Sample of our revision notes as a printable PDF.

Join Now
Go to Top