A-level · Quantities & units

Modelling assumptions & SI unitsExam-style questions

What each standard modelling word actually lets you ignore — particle, light, inextensible, smooth, rigid, uniform — so you can read an assumption off a question and know its consequence, the SI units mechanics is built on, and how to answer "state a limitation" by naming what the model leaves out.

Start practising Read the lesson

6 questions · A-level level · mark scheme and worked solution on each · no sign-up to try

DifficultyAllLevel 2Level 3
  1. 1
    In mechanics, explain what is meant by modelling a body as a "particle", and give one advantage of doing so.
    Level 2 · 2 marksTry it
  2. 2
    A string is modelled as "light and inextensible". State what each of these assumptions means.
    Level 2 · 2 marksTry it
  3. 3
    State what is meant by modelling a surface as "smooth", and how this affects the forces in a problem.
    Level 2 · 2 marksTry it