Question

a scientist uses a submarine to study ocean life. she begins at sea level, which is an elevation of 0 feet. she travels straight down for 112 seconds at a speed of 0.8 feet per second. she then travels directly up for 120 seconds at a speed of 0.6 feet per second. after this 232 - second period, how much time, in seconds, will it take for the scientist to travel back to sea level at 3.5 feet per second? if necessary, round your answer to the nearest tenth of a second.

Explanation:

Step1: Calculate distance traveled down

Distance = speed×time. The speed of going down is 0.8 feet per second and time is 112 seconds. So the distance traveled down is $0.8\times112 = 89.6$ feet.

Step2: Calculate distance traveled up

The speed of going up is 0.6 feet per second and time is 120 seconds. So the distance traveled up is $0.6\times120=72$ feet.

Step3: Calculate the remaining distance to sea - level

The net distance below sea - level is the distance traveled down minus the distance traveled up. So it is $89.6 - 72=17.6$ feet.

Step4: Calculate the time to reach sea - level

Time = distance÷speed. The speed is 3.5 feet per second and the distance is 17.6 feet. So the time is $\frac{17.6}{3.5}\approx5.0$ seconds.

Answer:

5.0