Question

An observation deck extends 202 feet out above the valley. The deck sits 152 feet above the valley floor. If an object is dropped from the observation deck, it's height h in feet, after t seconds, is given by h= -16t^2+152. How long will it take for the object to be 8 feet above the valley floor?

Answer 1

3 secs

Explanation:

Given the height of the object as it drops from the observation deck expressed as;

h= -16t^2+152

To determine the the time it will take the object to be 8 feet above the valley floor, we will substitute h = 8 into the equation and calculate t as shown;

8 = -16t^2+152

subtract 8 from both sides

8-8 = -16t^2+152-8

0 = -16t^2+144

0-144 = -16t^2

-144 = -16t^2

16t^2 = 144

Divide both sides by 16;

16t^2/16 = 144/16

t^2 = 9

t = √9

t = 3seconds

Hence it will take 3 seconds for the object to be 8 feet above the valley floor