Hi Professor Ditchko,
For part c, (solving for the total energy), I set the force of gravity equal to the spring force (with x = 0.36 m) and solved for k (31.3 N m). I then used the total energy equation 1/2(K A^2) and came up with 6.6 J. Why is this wrong? Can I not use the given x=0.36 as the equilibrium position here?

I apologize but I made a mistake with my original question. I multiplied 1/2 K value (31.3 N m) by the amplitude squared (.65), not by the equilibrium value x=.36 m.
Sorry about that!

## Comments

Hi Professor Ditchko,

For part c, (solving for the total energy), I set the force of gravity equal to the spring force (with x = 0.36 m) and solved for k (31.3 N m). I then used the total energy equation 1/2(K A^2) and came up with 6.6 J. Why is this wrong? Can I not use the given x=0.36 as the equilibrium position here?

Thanks so much!

I apologize but I made a mistake with my original question. I multiplied 1/2 K value (31.3 N m) by the amplitude squared (.65), not by the equilibrium value x=.36 m.

Sorry about that!