Forces in One Dimension


Forces can be classified several ways:

  • A force is a push, a pull, a bend or a twist.
  • Force is a vector quantity, and therefore needs magnitude and direction.
  • Force is measured in newtons (N).
  • A force is anything that attempts to change the motion of an object.
  • If an object is at rest, a net force can move it.
  • If an object is moving, a net force can change its velocity by making it go faster, slower, or in a different direction – i.e. by accelerating it.

Resultant forces can be solved by adding individual forces together.

Example 1:

Forces of 5N to the right and 10N to the right act on an object. What is the resultant force acting on the object?

F_{ 1 }=5N\quad right

F_{ 2 }=10N\quad right

{ F }_{ net }=5N+10N

{ F }_{ net }=15N\quad right


When considering examples of forces acting in one dimension it is important to remember that forces are vectors. This means that direction must be considered when calculating resultant forces. In one dimension this is done by making one direction positive and the other negative.

Example 2:

Forces of 4N to the right and 11N to the left act on an object. What is the resultant force acting on the object?

F_{ 1 }=4N\quad right

F_{ 2 }=11N\quad left

Using left as positive:

F_{ 1 }=-4N

F_{ 2 }=11N

F_{ net }=11N+(-4N)

F_{ net }=7N

As left is positive:

F_{ net }=7N\quad left

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