# A spring of natural length 80cm with a load has a length of 100cm. If it is slightly pulled…

Q: A spring of natural length 80cm with a load has a length of 100cm. If it is slightly pulled down and released its period will be

(a) 3s

(b) 0.9s

(c) 0.81s

(d) 2s

Ans: (b)

Sol: kx = mg => m/k = x/g

$\displaystyle T = 2\pi \sqrt{\frac{m}{k}}$