To remove the sludge at the bottom of the well,the grab bucket is put into the bottom ofthe well with the cable,and the well head is raised after grabbing the sludge.The well isknown to be 30m deep,the grab bucket has 400N weight,the cable has 50N weight permeter,and the sludge grabbed by the grab bucket has 2000N weight and the lifting speedis 3m/s.In the process of lifting,the sludge leaks out of the gap in the grab at a rate of20N/s.Now lift the grab to the top of the well and ask how many joules of work is requiredto overcome gravity?(①1Nx1m=1J;M,N,S,and represent meters,Newtons,seconds,and joules.2 The height of the grab and the length of the cable above thewellhead are ignored.)