Question

An observation deck extends 311 feet out above a valley. The deck sits 261 feet above the valley floor. If an object is dropped from the observation​ deck, its height h in​ feet, after t​ seconds, is given by h=-16t²+261. How long will it take for the object to be 5 feet above the valley​ floor?

Answer 1

• 4 seconds

Explanation:

Find the value of t in the following equation:

• -16t² + 261 = 5
• -16t² = - 255
• t² = 255/16
• t = √255/4 ≈ 4 seconds