Q: A spring of force constant k is cut into two pieces such that one piece is double the length of the other. Then the long piece will have a force constant of
(a)(2/3)k
(b)(3/2)k
(c)3 k
(d)6 k
Ans:(b)
Sol: $\large l_1 = \frac{2}{3} l \; and \; l_2 = \frac{1}{3}l$
k l = constant
$\large k l = k_1 l_1$
$\large k l = k_1 \times \frac{2}{3} l $
$\large k_1 = \frac{3}{2}k$