If you do not check the document carefully, you will miss some significant detail
Answer:
<em>c = -30 N</em>
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Explanation:
Initial length L1 = 30 cm
Initial restoring force F1 = -35 N
Final length L1 = 90 cm
Final restoring force F2 = -125 N
Between 30 cm and 90 cm, one will increase extension by 20 cm 3 times. This means the force between -35 N to -125 N increased by 3 constant value.
-125 - (-35) = -90 N.
this means that the constant is,
<em> c = -90/3 = -30 N</em>
<em>This means that for every 20 cm increase, there is a 30 N decrease in the restoring force</em>
