Question

After visiting the Titanic, Captain Brain and Mr. Pinky are taking the Alvin submarine back to the surface of the water. They start 1500 feet underwater. After ascending for 6 hours, they are 1380 feet below the surface of the water. (Note: under the water is negative)Write and equation to model this situation (use d for depth in meters and x for hours).

Answer 1

Variables

d: depth, in ft

x: time, in hours

The first point is (0, -1500) that is, at zero hours, they were 1500 ft underwater

The second point is (6, -1380), that is, at six hours, they were 1380 ft underwater

The slope of the line that connects these two points is:

$m=\frac{-1380-(-1500)}{6-0}=\frac{120}{6}=20\frac{ft}{h}$

From the point (0, -1500) the y-intercept of the line is b = -1500

Using the slope-intercept form of the line we get:

y = mx + b

d = 20x - 1500