A force is anything that can change a body’s state of motion — accelerating it, slowing it down or deflecting it — or deform it. Pushing a trolley, stretching a spring, the weight that keeps us glued to the ground: these are all forces, and they all act with a certain magnitude, along a certain direction and in a certain sense.
Principle — Force is a vector
A force is characterised by three elements:
- a magnitude (how intense it is), measured in newtons (N);
- a direction, the line along which it acts;
- a sense, the orientation along that direction.
Two forces add according to the parallelogram rule, or equivalently by adding their components.
Since force is a vector, when several forces act on a body at the same time their overall effect is given by the resultant force, i.e. the vector sum of all applied forces. Breaking each force into its components along suitable axes makes this calculation purely algebraic, and is the standard strategy for analysing a body’s equilibrium or motion.
Historical note — The newton
The unit of measurement of force, the newton, is named after Isaac Newton. It equals , i.e. the force needed to give a mass of an acceleration of .
Collegamenti
Argomenti: Vettori · Statica ed equilibrio Competenze: Scomposizione vettoriale
Esercizi collegati: Esercizio svolto — Itinerario Imola-Lugo · Problema — Vero o falso sui vettori · Problema — Risultante di due forze