Question

A bubble at the bottom of lake rises to surface within 10.0 seconds with an acceleration of 10.0 meters per second. What is the depth of the lake?

Answer 1

If the bubble travels 10 meters per second and it takes 10 seconds, then just multiply the distance per second by the total seconds to get the total depth.
10 • 10 = 100
The lake is 100 meters deep.

Think of it this way to clarify the answer:
It takes a bubble traveling at a speed of 10 meters per second 10 seconds to travel 100 meters.