Measurement and Uncertainities

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Can you guys help me, I do not understand this page.
Graph of F/N against x/cm with error bars on data points and a blue best-fit line through the origin, labelled Figure 1.7 with a caption about tension in a spring.


Can someone explain this page to me please, Especially the part where it says (0.0390, 7.88).

By the way, I am new here.
 
Do you understand how you must proceed to find the slope (or gradient) of a straight line? If so, please post an explanation to make sure that you do.
 
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kuruman said:
Do you understand how you must proceed to find the slope (or gradient) of a straight line? If so, please post an explanation to make sure that you do.

Yeh, It is just (y2 - y1)/(x2 - x1)Here what I don't understand is why are they choosing 0.039 as a x value why can't they choose another point.
 
Anonymous1 said:
Yeh, It is just (y2 - y1)/(x2 - x1)Here what I don't understand is why are they choosing 0.039 as a x value why can't they choose another point.
You will notice that they chose the extreme points on the graph, the origin and the highest value. This reduces the error when you do the division. If the points are too close to each other, then the error in the estimate will be larger.

On edit: 0.039 m = 3.9 cm. That's the value in SI units at which the force is 7.88 N.
 
kuruman said:
You will notice that they chose the extreme points on the graph, the origin and the highest value. This reduces the error when you do the division. If the points are too close to each other, then the error in the estimate will be larger.

Oh yeh true,
thank you so much