Finding the uncertainty of this problem

[charmedbeauty]

Homework Statement

When a mass of 166.5 ± 3.0 g is added to a spring the spring extends 7.20 ± 0.16 cm.

What is the uncertainty in the spring constant, k? You may assume g is known precisely with no uncertainty.

Homework Equations

The Attempt at a Solution

I just converted the units so 3.0 g = 0.003kg

and 0.16cm = 0.0016 m

so to find uncertainty I just did (0.003)(9.8)+(0.0016)

but that was wrong??

can someone please tell me what I am doing wrong here?

 

[flatmaster]

These problems can be quite confusing. In this case, you first find the spring constant with the mass and extention without the uncertainties. Secondly, calculate the spring constant with maximum uncertainty. The next step is up to you.

 

[charmedbeauty]

These problems can be quite confusing. In this case, you first find the spring constant with the mass and extention without the uncertainties. Secondly, calculate the spring constant with maximum uncertainty. The next step is up to you.

then find it with minimum uncertainty and divide by 2??

 

[flatmaster]

Sounds good to me.

 

[Steely Dan]

then find it with minimum uncertainty and divide by 2??

That will just get you the average spring constant, which you already know since the error is symmetric with respect to the average. Instead, the uncertainty is just the difference between the average and the maximum uncertainty one (or the average and the minimum uncertainty one).

 

[charmedbeauty]

That will just get you the average spring constant, which you already know since the error is symmetric with respect to the average. Instead, the uncertainty is just the difference between the average and the maximum uncertainty one (or the average and the minimum uncertainty one).

would that be the max of mass and extension or just the mass??
and the average would that be the average of mass and extension?? Thanks..