Editor's Note: The Hyperloop is a totally imaginary transportation device that has captivated entrepreneur Elon Musk, who keeps talking about it. First imagined at least 100 years ago, it would ...

Imagine you want to study what happens when an object accelerates. Oh, this is way before any of that internet stuff—also, no computers or electronics. In fact, let's say it's the year 1780. What do ...

A horizontal line means the object is moving at a constant speed. The gradient of the line = the rate of change of speed. The steeper the line, the greater the increase in speed. The area under the ...