The total length of a spring when a mass of 20g is hung from its end is 14cm, while its total length is 16cm when a mass of 30g is hung from the same end. Calculate the unstretched length of the spring assuming Hooke's law is obeyed.
A
9.33cm
B
10.00cm
C
10.66cm
D
12.00cm
E
15.00cm
Verified Correct Answer: B.
Physical Principles & Numerical Solution
Let unstretched length = L
e1 = 14 - L and e2 = 16 - L
Using, \(\frac{m_1}{e_1}\) = \(\frac{m_2}{e_2}\)
\(\frac{20}{14 - L}\) = \(\frac{30}{16 - L}\)
L = 10cm
Source: Myschool Past Questions Archive (Record #28864)