velocity can either be positive or negative, depending on the direction of the displacement. the (change t), is always positive. why?

Answer 1

Hi Addison,

The short answer is because we are always moving forward in time.

This means that when you measure a change in time the final time is always greater than the time when you started. Unless we moved back in time, of course :)

To be complete, note that the change in time does not always have to be positive in a problem. I mean, you could have a problem where you are given some information about displacement, and/or velocity, and/or acceleration at one time and are asked to find out what the objects displacement, and/or velocity, and/or acceleration was at a previous time. These problems are more rarely given.

Hope this helps!

Bye,

Raphael