Question

If the work required to stretch a spring 1 ft beyond its natural length is 12 ft-lb, how much work is needed to stretch the same spring from its natural length to 3 in? Hint: 1 ft = 12 in

Answer 1

Answer:$W=\frac{3}{4} ft-lb$

Explanation:

Given

Work required to stretch 1 ft is 12 ft-lb

and we have to find work required to stretch 3 in.

i.e. $\frac{1}{4} ft$

$12=\frac{1}{2}K\left ( 1\right )^2 ------(1)$

$W=\frac{1}{2}k\left ( \frac{1}{4}\right )^2-----(2)$

divide (1)&(2)

$\frac{12}{W}=\left ( \frac{4}{1}\right )^2$

$W=\frac{12}{4\times 4}$

$W=\frac{3}{4} ft-lb$