Linear motion

When modelling a particle moving in a single direction, we’re working with one-dimensional motion, otherwise known as linear motion.

Direction

With linear motion, we have to define one direction as positive and one direction as negative.

For example, we may decide that:

Motion to the right is positive and to the left is negative, or perhaps,
Motion upwards is negative and motion downwards is positive.

As long as it is clearly defined, you can choose whatever you like.

We use this

Question	Answer
In linear motion modelling, what must be defined before starting?	One direction as positive and one direction as negative (e.g., right = positive, left = negative).
When defining direction for linear motion, what choices can you make?	Any choice is allowed as long as it is clearly defined (e.g., upward = negative, downward = positive).