Paper 2 · Module
Quantities and units in mechanics
Modelling assumptions and their meaning
Mechanics replaces messy real objects with simple models. Each modelling word has an exact meaning: a particle has no size, a light object has no mass, a smooth surface has no friction, an inextensible string doesn't stretch. Knowing what each word lets you ignore is half of every M1 question.
≈ 25 minQuantities, units and evaluating models
Mechanics works in SI units: metres, kilograms, seconds and the newtons built from them. Convert before you calculate. Some quantities are scalars (size only) and some are vectors (size and direction). Once a model gives an answer, ask what it ignored and how that would change the result.
≈ 25 min