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when you draw a graph..

when do you extrapolate?
when do you draw a line of best fit?
do you start from origin?

thanks
 

youngminii

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Physics/Chem?
ALWAYS draw a line of best fit. Always.
Never start from the origin unless the data given says so (some schools penalise, some schools don't).
 

tommykins

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also never draw an unbroken line past the data in which you have.
 

xV1P3R

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Well if it's intuitive for example, graphing ohm's law on a graph, zero voltage would intuitively result in zero current, I would definitely make the graph go through the origin and alter the line of best fit.
 
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line of best fit with a ruler?
or hand drawn?

or does that depend on whether we know the gradient will be a straight line
 

adomad

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line of best fit with a ruler?
or hand drawn?

or does that depend on whether we know the gradient will be a straight line
if you can see that the dots roughly form a straight line, then use a ruler. if it is obviously going to be a curve, go over the path that the curve is going to take by hovering you hand above it. once your happy with that motion that you are doing with your hand, then put pencil to paper.

you only use a line of best fit if you want to show the relationship between the x and y axes. trend graphs, you join the dots (learn't that the hard way in a chem exam):(
 

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