Now there's a question that sounds to have a strangely obvious answer... But I am bored, so why not ask stupid questions on Seabreeze.
Speed is a scalar quantity and velocity is a vector quantity, right?
Speed can be expressed in any distance/time units you want, too?
Now, if I were to travel for 100km from Perth and then return in 2 hours, my 'speed' would have been 100km per hour, right?
During that period of travel, my actual velocity could have varied up to "200kph" and down to "0kph". But my speed is still 100kph because I am measuring speed in kilometres and hours.
I never did physics in high school, but is that above correct?
Average, yes.
it's an application of two different quantities to work the other third quantity out.
if you want to know required speed, or what speed you've averaged, then it's distance divided by time.