(Solved): 15.165 At the instant shown, the length of the boom AB is being increased at the constant rate of ...

15.165 At the instant shown, the length of the boom $AB$ is being increased at the constant rate of $0.2\mathrm{m}/\mathrm{s}$, the boom is being lowered at the constant rate of $0.08\mathrm{rad}/\mathrm{s}$, and the truck is moving forward with a speed of $0.1\mathrm{m}/\mathrm{s}$ and is slowing down at $0.05\mathrm{m}/{\mathrm{s}}^2$. Determine $(a)$ the velocity of point $B,(b)$ the acceleration of point $B$.