Elastic energy, spring equation. Help?

[mrphobio]

Homework Statement

A 293g block is placed on a spring with a spring constant of 161N/m, compressing it 42cm. What height does the block reach when it is launched?

Homework Equations

Eel=1/2*k*x²
Eg=mgh

The Attempt at a Solution

Eg=.293*10*.42=1.2306

1.2306=1/2*161*x²
1.2306=80.5x²
.0153=x²
.1236=x

Did I make any mistakes? Because I can't get it right.

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nevermind i got it..

 

[TaxOnFear]

Hi mrphobio,
You're using the equations the wrong way round.
The energy stored in the spring (0.5kx²) with spring constant k and compression of the spring x.

Since energy can't be destroyed, it is transformed into kinetic energy, and finally into potential energy (mgh) with mass m and height of the object h.

Hope this helps.