# If a spring has a constant of 4 (kg)/s^2, how much work will it take to extend the spring by 19 cm ?

Hooke's law says that $F \propto \Delta x$, or $F = k \Delta x$. In this question we know both the extension, and spring constant, so we just have to do 0.19x4=0.76N.
The question however asks for work done, which is represented by $W = F \Delta s$, $\Delta s = \Delta x$. We just need to do 0.76x4=3.04J of work.