more from Isaac Newton

### Single Idea 17018

#### [catalogued under 27. Natural Reality / A. Classical Physics / 1. Mechanics / b. Laws of motion]

Full Idea

Law 2: A change in motion is proportional to the motive force impressed and takes place along the straight line in which that force is impressed.

Gist of Idea

2: Change of motion is proportional to the force

Source

Isaac Newton (Principia Mathematica [1687], Axioms)

Book Reference

Newton,Isaac: 'Philosophical Writings' [CUP 2004], p.71

A Reaction

This gives the equation 'force = mass x acceleration', where the mass is the constant needed for the equation of proportion. Effectively mass is just the value of a proportion.