A "cross section" is basically the two-dimensional face that you get when you cut a three-dimensional figure a certain way. For example, imagine you're buttering your bread. When you cut a pat of butter off, what shape is left on the butter? A square!
So, imagine cutting a ball in half. What shape is left? A circle!
No because she can run slow and waste time and not get that far and it will be 3 min. But if you go fast and stop at the same distance it won’t take as long because of your SPEED.
