Question

The altitude of Death Valley, California, is 282 feet below sea level. A hot air balloon is launched from the bottom of Death Valley and rises at a rate of 10 feet per second. After 12 seconds, the balloon captain lowers the balloon 15 feet. What is the altitude of the hot air balloon after being lowered? A) 177 feet below sea level B) 105 feet above sea level C) 162 feet below sea level D) 387 feet above sea level

Answer 1

In order to find the final altitude of the globe, you calculate the different distance traveled by the globe, just as follow:

First, the globe is at 282 ft below sea level. You can consider this as -282 ft (because it is below sea level, a minus sign is convenient)

The globe rises with a speed of 10 ft/s, after 12 seconds, the globe rises:

h = vt = (10ft/s)(12s) = 120 ft

Then, the globe rises 120 ft, you can take it as +120 ft

Next, the captain lowers the ballon 15 ft, you take it as -15ft.

You sum the previous vertical distances traveled by the globe:

-282 ft + 120 ft - 15 ft = - 177 ft (remind minus sign means below level sea)

Hence, the globe, after the complete trajectory will be 177 feet below sea level.