CPM Homework Help : PC Problem 4-143

Sean just got a toy rocket that flies at a rate of $v = 30t$ feet per second. The rocket is designed to fly straight up for ten seconds and then release a parachute and float back down. At what height will the parachute be deployed?

Hint:

The height will be represented by the area under the curve $v = 30t$ between $t = 0$ and $t = 10$ seconds.

Why does area represent distance?