Falling brick speed - equation needed

[[Cat]]

I have a question in my work book that I cannot solve as I can't find the correct equation. The question is:

What speed will the brick have after falling through a distance of 20 metres? U= at rest. There are no other constants given. What equation would I use to solve this problem?

(I have looked in the back of the book and the answer is:19.8 m/s)

Thanks,
Cat.

 

[bsmith2000]

Think conservation of energy. Compare the initial and final energies at each state and equate them.

 

[rem]

v**2=u**2+2as