Force and Mass

Summary

• Newton's second law of motion (also known as the force law) states that…
  • acceleration is directly proportional to net force when mass is constant, and…
  • acceleration is inversely proportional to mass when net force is constant, and consequently…
  • net force is directly proportional to mass when acceleration is constant.
• Newton's second law of motion is more compactly written as the equation…

  ∑F = ma

• Mass
  • Mass is a measure of resistance to acceleration. More generally, mass is a measure of resistance to all sorts of change.
  • Mass is a scalar quantity associated with matter.
  • When a system is composed of several objects it is the total mass that matters.
  • The SI unit of mass is the kilogram [kg].
    • The kilogram is one of the seven base units of the International System of Units
• Force
  • A force is an interaction that causes acceleration. More generally, a force is an interaction that causes a change.
  • A force is a vector quantity associated with an interaction.
  • When several forces act on a system it is the net, external force that matters.
  • The SI unit of force is the newton, named after the English physicist and mathematician Isaac Newton (1642–1727).

    [N = kg m/s²]

• Supplementary Materials
  • Summary as a concept map
  • Original statement in Latin from Newton's Principia with English translation