Question

PageSavvas EasyEridgeAn observation deck extends 118 feet out above a valley. The deck sits 68 feet above the valley floor. If an object is dropped from the observation deck, its heighth in feet, after t seconds, is given by h= - 16t? + 68. How long will it take for the object to be 4 feet above the valley floor?It will take seconds for the object to be 4 feet above the valley floor.(Type an integer or decimal

Answer 1

Given data:

The height of the desk above the valley is 68.

if an object is droped from the desk the height after t seconds is ,

`h=-16t^2+68`

put h = 4 in the above equation.

`\begin{gathered} h=-16t^2+68 \\ 4=-16t^2+68 \\ 16t^2=68-4 \\ 16t^2=64 \\ t^2=(64)/(16) \\ t^2=4 \\ t=\pm\sqrt[]{4} \\ t=\pm2 \\ t=2 \end{gathered}`

t=2 because time can only be positive.

thus, it will take 2 seconds for the object be 4 ft above the valley floor.