# Curve fitting for Gravity/Conservation of Energy Lab

## Homework Statement

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The problem has to do with sig figs going down to 1. I've checked them multiple times by hand and with sigfig calculators but it is all the same. With 1 sig fig my standard deviation ends up being 0 which I am not sure that is acceptable.
It makes sense as the points are super consistent for measuring G but when it comes to filling out the tables having 0 for most parts bothers me.

V^2=g(2H)
Y=mx+b

## The Attempt at a Solution

I have an excel document with all my data and calculations

#### Attachments

• measuring g.xlsx
30.8 KB · Views: 135

andrevdh
Homework Helper
It seems that you calculated the h (or Δh) values incorrectly since you are using the same angle, θ or L2, for each run? Or did you keep the angle the same and released the glider at progressively lower points along the track?

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It seems that you calculated the h (or Δh) values incorrectly since you are using the same angle, θ or L2, for each run? Or did you keep the angle the same and released the glider at progressively lower points along the track?
We kept the angle the same and changed the release point for each set of runs

BvU
Homework Helper
0 is not the same as an error in one significant figure.
One significant figure means you take the first nonzero digit, so your ##\sigma_g## is 0.06

(In case the first nonzero digit is a 1, we often take the first two digits - because the step from 1 to 2 is so big - and still speak of one significant digit. But it depends: with the relative error in the sigma approximately ##1/\sqrt N## and 5 observations you understand that ##\sigma## itself isn't very accurate at all)​

So as a result you have ##g = 9.56 \pm 0.06 ## m/s2 for the light glider - and have to say something reasonable about the intercept ##0.055 \pm 0.024## (here I show two digits -- the intercept is 2##\sigma## from zero, which may or may not give you a reason to fit y = m x instead of y = mx + b) .

BvU