Apenny is dropped from the top of a 1,000-foot building. the function gives the height of the penny t seconds after it starts falling. how long will it take for the penny to reach the ground? round the answer to the nearest tenth of a second.

We consider an approximation of the gravity g=10. 
Then the speed is given by the formula: s(t)=10t.
And the coordinate is given by the formula:x(t)=5t^2+t
(integrating the speed function).
Now set up the equation:

Solving the above equation for t we get:t =14 seconds. 
It will take 14 seconds for the penny to reach the ground.