**an object is dropped from a building 100ft tall. the distance s in feet from the top t seconds later is given by s=16t^2. what is the velocity when it hits the ground?**

**Answer:**

First solve for t by setting s equal to 100, because that will be the distance from the top of the building when the object hits the ground.

100 = 16t^2

t^2 = 6.25

t = 2.5

Then, since velocity is equal to the change in distance over time, you can divide the change in position (final minus initial, 100 - 0) by the time (above, 2.5 sec) and it will give you your velocity.