问答题 (清华大学2006--2007学年春季学期期中考试试题)as in Fig．4-62，A liquid jet of velocity V _j and area A _j strikes a single 180°bucket on a turbine wheel rotating at angular velocity Ω．Find an expression for the power P delivered．At what Ω?is the power a maxi mum?How does the analysis differ if there are many buckets，so the jet continually strikes at least one?