Question

The elevation at ground level is 0 feet. An elevator starts 70 feet below ground level. After traveling at a constant speed for 15 seconds, the elevator is 120 feet below ground level. Which statement describes the elevator's rate of change in elevation during this 15-second interval?

Answer 1

-3.33 ft. per second

Explanation:

The rate of change of an object can be calculated by finding the difference in position between the starting point and end point, and then dividing by the difference in time between the starting time and end time. Using the values provided in the question we can calculate the following

`(120ft - 70ft)/(15s - 0s)` = 3.33 ft. per second

With the calculation above we can see that the rate of change during these 15 seconds is 3.33 ft. per second. Since the endpoint is further down below ground level then we were descending which means that the rate of change would be a negative (-3.33 ft. per second)