Spring Constant (NEED HELP !)

1. Problem

A spring with a pointer attached is hanging next to a scale marked in millimeters. Three different packages are hung from the spring, in turn, as shown below.

07_39.gif


(a) Which mark on the scale will the pointer indicate when no package is hung from the spring?
(a) ? mm

(b) What is the weight W of the third package?
(b) ? N

2. Attempt at a solution

240 N - 110 N = 130 N
60 mm - 40 mm = 20 mm

130 N = -k * 20 mm <-- Is this formula correct? If not, how do I find the answers to (a) and (b)?
k = -6.5
 

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Last edited:
Never mind. I found the answers.

(a) 23 mm
(b) 45 N

Thanks for nothing. lol.
 
Last edited:

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