Spring Calibration Data -> Need to figure out formula

[mcdowellmg]

Spring Calibration Data --> Need to figure out formula

I feel like every time I post a problem here, I end up figuring it out. So, thanks for that! haha

 

[mcdowellmg]

Another question. I am supposed to find the expected slope of a line that will help me realize that ac = rω2.

expected slope = –4*pi^2(µ/g)(Mg/k) =

I know that (Mg/k) = 5.3. I know that µ = 5. I am GUESSING that g = 9.8 or -9.8, but both of the answers 106.753 or -106.753 are not correct. I cannot figure this out, so thanks for any help!