Why Is Measuring Jupiter's Mass Using Its Four Largest Moons More Accurate?

[Bashyboy]

Homework Statement

I've attached the lab sheets for the lab I am currently working on, and I am wondering if someone could help me with it.

Homework Equations

The Attempt at a Solution

I am having difficulty with part two, steps 5-8. I have the slope from my excel graph 0.6458, what units would this be in? I have the y-intercept, 12.347, again, what units would this be in? Supposedly its the mass of Jupiter. I don't know how to find the correlation coefficient, nor the 95% ranges, nor the confidence interval. How do I find these things in Excel?

I'm sorry if this isn't typed us so neatly, it's just that I have to hand this in today; so, I'm a bit frantic. I would certainly appreciate your help, though.

 

[Bashyboy]

Oh, I forgot to mention: I tried to upload the excel sheet, thinking it might make things more clear, but it wouldn't work. The file type is .xlsx, is there some way to change the file type, so that it may upload?

 

[SteamKing]

You'll have to save your Excel sheet as a different file type (usually a previous version of Excel)

 

[Bashyboy]

All right, I was successful in uploading.

 

[vela]

Usually the argument and result of a function are unitless, but the logarithm doesn't follow this rule. I wouldn't worry too much about the units.

To find the other stats, look at the LINEST function in Excel. For the confidence intervals, look into http://en.wikipedia.org/wiki/Simple_linear_regression, particularly the numerical example at the bottom. I don't know offhand if Excel can calculate those for you.

 

[Bashyboy]

I figured it all out. Thanks, Vela However, I have one more question: why is it more accurate to measure the mass of Jupiter in terms of the four largest moons, than to measure the mass of Jupiter in terms of all 16 moons? Does it have something to do with the gravitational pull of those large moons on the smaller ones? If why, would someone care to help me understand this? I can see mathematically that it is true, I just want to have some physical intuition as to why it's true.