How Do You Calculate Percent Error in a Conservation of Energy Lab?

[bwilhelm]

Homework Statement

I am trying to calculate a percent of error in a conservation of energy lab, and for some reason I am completely drawing a blank.
Just so you know what I am looking at,
I have about 10 values or so in 3 columns labeled KE, PE, E. E is KE + PE

Homework Equations

I wrote down (Elast - E1st)/ (Etotal) and then multiply by 100. Something just seems wrong here and I don't know why. Is that correct?

The Attempt at a Solution

 

[member 553083]

No, this formula is incorrect. The correct formula to calculate percent error in a conservation of energy lab is (|Etotal - Elast|)/Etotal * 100. This formula calculates the absolute value of the difference between the total initial energy and the total final energy, then divides it by the total initial energy, and multiplies it by 100 to get the percent error.