Question

A force of $20N$ is required to stretch a spring a distance of $40cm$from its rest position. what force (in Newtons) is required to stretch the same spring twice the distance.

• A. $20N$
• B. $40N$
• C. $80N$
• D. $160N$

Answer 1

The correct option is B $40N$

As more the extension, more is the force required. Force and stretch are proportional to one another such, that if you double the force, the amount of stretch will double.
$F_1=k{x}_1$
$20=k\times 40$
Thus spring constant $k=\frac{1}{2}N/m$
$F_2=k{x}_2$
$F_2=\frac{1}{2}\times 2\times 40$
$F_2=40N$