How To Make A Straight Line Fit Using Excel?
Let's consider the following example:
One has measured the force necessary to extend a spring from its rest (equilibrium
position) for various extensions. The goal is to find the spring constant. The theory (Hook's Law)
predicts the linear dependence between the force and the change of the length of the spring:
F = -kx
To find the spring constant k, one needs to plot the negative force -F as a function of x and
find the straight-line fit. The slope of that line is equal to the spring constant k.
Finding the best straight-line fit could be quite time consuming if done with a calculator.
Using Microsoft Excel program significantly simplifies the whole procedure. Follow the steps
shown below to make a graph and then draw a straight line that fits your data.
A. Start Microsoft Excel 2010 (or Excel 2007).
B. Enter your data into Excel spreadsheet.
C. Highlight all cells containing data. In our example, the first column (A) contains values of x,
whereas the second column (B) contains values of force -F:
D. From the "Insert" tab select "Charts - Scatter". Use the first type of scatter charts – “Scatter
with only Markers”.
You should see a simple plot prepared by Excel.