Energy, work and power — practice question

A block of mass $60\,\text{kg}$ is drawn up a hill along the line of greatest slope by a force of magnitude $50\,\text{N}$ acting at an angle $\alpha^\circ$ above the hill. The block moves through points $A$ and $B$ with speeds $8.5\,\text{m s}^{-1}$ and $3.5\,\text{m s}^{-1}$ respectively (see diagram). The separation $AB$ is $250\,\text{m}$ and $B$ is $17.5\,\text{m}$ above the level of $A$. The resistance to motion of the block is $6\,\text{N}$.