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Physics vocabulary · Motion and Forces

Normal force

Meaning in physics, with examples

nounCommon term

In physics, normal force means: The push from a surface on an object that rests on it or presses against it. It always acts at right angles (normal) to the surface.

In Turkish: normal kuvvet, tepki kuvveti

How it is used

Symbol N or R; British books also call it the normal reaction or normal contact force. It is not always equal to the weight: on a slope it is mg cos θ, and in an accelerating lift it changes. Friction depends on it: f = μN.

Example sentences

  1. On a 30° slope, the normal force on the block is smaller than its weight.

  2. A bathroom scale actually measures the normal force between your feet and the scale.

Common collocations

  • normal reaction
  • normal contact force
  • reaction force
  • normal to the surface
  • forceA push or a pull that can change how an object moves or change its shape. It has both size and direction and is measured in newtons (N).
  • weightThe force with which gravity pulls on an object. It equals mass times the gravitational field strength (W = mg), is measured in newtons and changes from planet to planet.
  • frictionA force that acts between two surfaces in contact and opposes their sliding past each other. It usually turns kinetic energy into heat.
  • free-body diagramA simple sketch of one object with labelled arrows for all the forces acting on it, each drawn in its own direction. It is the usual first step in solving a forces problem.
  • Newton's laws of motionThree basic laws that describe how forces affect motion: an object keeps its state of motion unless a net force acts, net force equals mass times acceleration, and every action has an equal and opposite reaction.

More terms: Motion and Forces

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