Question

A rock is dropped from a height of 25 feet. The function h=-16t^2 +25 gives the height h of the rock after t seconds. When does it hit the ground?

Answer 1

5 seconds

Explanation:

The ground is 25 eet, so 25=-16t^2+400

-16t^2=-400, 16t^2=400

t^2=25, dividing both sides by 16

t=5 seconds.