Force

How it is used

The central word of mechanics. A force acts on, is applied to or is exerted on an object; forces can be balanced or unbalanced, and you add them as vectors. Teachers often ask students to 'draw all the forces' before solving a problem.

Example sentences

1. A force of 20 N acts on the box at an angle of 30° to the horizontal.

2. If the forces on the car are balanced, it keeps moving at a constant velocity.

Common collocations

• apply a force
• exert a force
• a force acts on
• balanced forces
• resultant force

Related terms

• net forceThe single force that has the same effect as all the forces acting on an object together. It is the vector sum of those forces and decides the object's acceleration.
• 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.
• 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.
• vectorA quantity that has both a size (magnitude) and a direction, such as displacement, velocity, force or acceleration. It is often drawn as an arrow.
• massThe amount of matter in an object, which also measures how hard it is to change the object's motion. It is measured in kilograms (kg) and does not depend on location.

More terms: Motion and Forces

• velocity
• acceleration
• gravity
• weight
• friction
• speed
• displacement
• equilibrium
• projectile motion
• inertia
• torque
• centripetal force