What is the relationship between ramp height and final velocity of a marble?

[16Candles]

Homework Statement

A marble is released from a 10cm ramp. Its final velocity is 1.4 m/s. If it is released from a 20cm ramp, twice the height, what will its final velocity be?

Homework Equations

E = mgy + mv^2/2
mgy = mv^2/2 (Like initial gravitational potential energy will equal final kinetic energy? Does that make sense?)

The Attempt at a Solution

I tried to use mgy = mv^2/2, where I get 2gy = v^2. For g, our physics teacher has us use 10 m/s^2, and if the height is 20cm, then (2*.2m*10m/s^2) = v^2, 400 = v^2, v = 2m/s, but I don't think that is right.

I asked my teacher for help, and he said to think about the relationship between the height and the velocity (which I think has to do with square roots, but other than that, I am lost).

 

[16Candles]

Never mind, I figured it out! :)