1. The problem statement, all variables and given/known data 2. Relevant equations P=FV 3. The attempt at a solution To calculate the mass of wind swept by turbine in a second, I take 2000m2 ×10ms-1×1.3kgm-3.Then, to calculate the force I multiply the answer with 10ms-1. Since they want the power and the yield is 50%. I multiply the answer again with 10ms-1 and divide it by two. This gives me C as the answer. However, the answer is B. So where did I go wrong?