Calculating Building Height: Quick Kinematics Question

[Cookies?]

A stone is dropped from the top of a building. Within the second before it hits the ground, it travels 1/5 of the building's height. Calculate the total height of the building.

Been trying to formulate simultaneous equations but there just doesn't seem to be enough information and too many unknowns >< Help appreciated!

 

[lep11]

What is the speed of the stone just before it hits the ground? You only need one equation.

 

[Doc Al]

Show what you've done so far. How would you write the distance fallen as a function of time?

 

[lep11]

You don't need more info either as the unknowns will eventually cancel out. There are actually a couple of different ways to solve this.