Show that $\mathrm{K}=\frac{{\mathrm{p}}^2}{2\mathrm{m}}$, where $\mathrm{K}$ is kinetic energy and $\mathrm{p}$ is momentum of a particle of mass $\mathrm{m}$. 

State with reasoning whether the work done in the following cases is positive or negative: A water bucket is pulled up from well