Why doesn't my force/ extension graph pass through the origin?

When F=ke is rearranged to fit into the equation for a straight line (y=mx+c), there is no value for c, so in theory there should be no y-intercept and the line should pass through the origin. In my graph, this is not the case.

Please could you give me an explination? It is not the first time I have calculated the extension of the wire and noticed this.

Why doesn't my force/ extension graph pass through the origin?hollywood theater

I think there must be something wrong with the way you are

1. plotting the results or

.2. collecting the data.

When there is NO LOAD then there cannot be any extension so it must pass through the origin.

Is it possibly that the wire is not taut before you apply the first mass?

You could check the diameter of the wire with a micro-meter gauge to see if there is any necking (shown by a decrease in the diameter).

Maybe you should give us your results so we can see what is happening. Remember Hooke's law states "within the elastic limit" you maybe exceeding it. Then Young's modulus applies.

Why doesn't my force/ extension graph pass through the origin?opera.com opera theater

Did you measure the extension as you added weights and again as you took them off so you know it was elastic ( no creep) ?

Are you plotting extension or percentage extension?

Is it within your measurement uncertainty?

best of luck - Mike
The specimen was probably not straight at the start or the extensometer was not quite engaged ,I can't tell which,I wasn't there.I dnt think it matters much but I suggest that, next time, you put some small ELASTIC strain into the system,then unload to zero stress and then adjust the your extension measuring to read zero.Question,Is the extensometer fixed to the grips of the mechanism or to the specimen itself?either of these should be OK .Of course I take it you didn't plastically strain the specimen and then expect it to return to zero strain.

To cut to the chase,dont place to much reliance on measurement of stain at very small loads.
the material you are measuring could have has strain put on it prior so it starts off with alot of strain already