Forces

Applied Mathematics — Second Secondary

A force is a vector quantity

A scalar quantity is known by its magnitude only, such as mass, time or length.
A vector quantity is known by its magnitude and its direction, such as velocity, displacement or force.
To specify a force completely we need three elements:

Key points

Magnitudemeasured in newtons, always a positive number.

Directiongiven by the angle it makes with an agreed horizontal direction, or in words such as east, upwards, or down the inclined plane.

Point of applicationthe point on the body where the force acts.

On a diagram a force is drawn as an arrow whose length is proportional to its magnitude.
The arrowhead shows the direction, and the tail is at the point of application.
For example, a force of 20 N drawn with the scale 1 cm for every 5 N is an arrow 4 cm long.

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