Chapter 6, Problem 9P

A force $\stackrel{\to }{F}=(6\hat{j}-2\hat{j})\text{ N}$ acts on a particle that undergoes a displacement $\Delta \stackrel{\to }{r}=(3\hat{i}+\hat{j})\text{ m}$. Find (a) the work done by the force on the particle and (b) the angle between $\stackrel{\to }{F}$ and $\Delta \stackrel{\to }{r}$.