Question

A submarine cuts through the water at an elevation of 203 meters under the sea. The sub rises, and the elevation changes by 4.3 meters per minute for the first 15 minutes. The sub continues to rise at 5.2 meters per minute for the next 12 minutes. What is the elevation of the submarine after rising? Assume that sea level is at an elevation of 0 feet.

Answer 1

The answer is -76.1 meters.

The submarine elevation before rising is -203 meters (it is negative because it is under the sea level which has 0 elevation): d₁ = -203 m
After the first rising, it moved 64.5 m: l₁ = 4.3 · 15 = 64.5 m
After the second rising, it moved 62.4 m: l₂ = 5.2 · 12 = 62.4 m

So, to calculate the elevation of the submarine after rising (d₂), we will add (because it is not going deeper, it rises toward the elevation of 0) two movements to the elevation before rising:
d₂ = d₁ - (l₁ + l₂) = -203 + (64.5 + 62.4) = -203 + 126.9 = -203 + 126.9 = -76.1.