Force
A vector interaction that, when unopposed, alters the state of motion or deforms a physical body.
Governing formula
F = m a = dp/dt
SI unit
N (kg·m/s²)
In depth
Forces arise from fundamental interactions (gravitational, electromagnetic, strong, weak) or contact forces (normal, friction, tension). Net force causes linear acceleration according to Newton's second law.
Examples in the real world
Gravitational force pulling an apple downward, or tension in a crane cable hoisting a heavy steel beam.