A cable weighing 0.8 pounds per foot is attached to a small 80-pound robot,and then the robot is lowered into a 50-foot deep well to retrieve a 7 pound wrench.The robot gets out of the well (carrying the wrench) by climbing up the cable with one end of the cable still attached to the robot.How much work does the robot do in climbing to the top of the well?
請看清楚哦，機器人是沿著繩子往上爬的，也就是說每時每刻它本身的重量在變化（繩子掛在它身上的部分隨著它往上爬也在增加） 所以不是單純的物理題目 我肯定是微積分的題目因為它就是在我書上這一個chapter的內(nèi)容啊。