Help Freefalling object problem

[akbro93704]

Homework Statement

A certain freely falling object requires 1.60 s to travel the last 23.5 m before it hits the ground. From what height above the ground did it fall?

Homework Equations

This is my last question on my online homework. Help! I have gotten answers, but the computer says they wrong.

The Attempt at a Solution

I know I have to set up two different equations, one for the last 23.5 m and one from the point that it fell at to the last 23.5m. I know the initial Velocity of the object is 0, and the final velocity of the initial drop is the initial velocity of the last 23.5m. Please help! I have tried it numerous times. My homework is due in 4 hours... Thanks :)

 

[mgb_phys]

You know the equations for a faling object.
v = u + gt
s = ut + 1/2 gt^2
v^2 = u^2 + 2gs

(s=distance, u=initial velocity, v=final velocity)
So you can work out the initial velocity ofthe last stage, and then use that as the final velocity of the first stage.