Plotting lab data on graph paper

The data

A trolley rolls down a track and you record its position every 5 seconds. You end up with this:

time (s):     0, 5, 10, 15, 20, 25, 30
distance (cm): 2, 8, 17, 24, 33, 41, 49

Seven points, monotonic, roughly linear — the kind of dataset a first-year physics lab spits out.

Choosing a scale

The paper defaults to 180 × 150 mm. The axis origin sits ~20 mm from the bottom-left edge, so the visible plot area is about 160 mm wide and 130 mm tall.

The time range is 0–30 s. If you want the data to span most of the paper width, set the X scale so that 10 s ≈ 50 mm: three labelled steps of 50 mm fill 150 mm of width nicely. In the controls panel:

X scale:  [ 10 ][ s ]  =  [ 50 ][ mm ]  on paper

The distance range is 2–49 cm. Picking 10 cm = 25 mm gives a tidy fit: five labelled steps of 25 mm fill 125 mm of height.

Y scale:  [ 10 ][ cm ]  =  [ 25 ][ mm ]  on paper

Entering the values

In the Data section, paste the comma-separated lists:

X values:  0, 5, 10, 15, 20, 25, 30
Y values:  2, 8, 17, 24, 33, 41, 49

The strip at the bottom shows Ready — 7 points plotted. Dots appear on the paper with dotted projection lines back to each axis, exactly where a ruler would put them.

Adding the regression line

Open the Connection section and pick Trend. The app computes the least-squares best-fit line:

y = m·x + b
  m = (n·Σxy − Σx·Σy) / (n·Σx² − (Σx)²)
  b = (Σy − m·Σx) / n

For this dataset the line lands at roughly y ≈ 1.58·x + 1.4 — a slope of about 1.6 cm/s, which is your trolley's mean velocity. The line is clipped to the visible plot area so it spans the paper even where you don't have data points.

Exporting

Use Print in the top bar for a paper print (the controls panel, top bar, and legend all hide automatically in print mode), or Export PNG for a 3× DPI raster you can drop into a lab report.

Try it now in the app →