A boy was racing a bear cub to the top of a tree. The boy, with a mass of 30 kg, would grab hold of a branch with his hands and use his arms to pull himself up with 500 newtons a distance
of 0.5 meters. He would then lift his legs over the branch and then use his legs to push against
the branch with 800 newtons to lift himself another 0.5 meters.
How much work did the boy do with his arms to lift himself over one branch?