Fluid Mechanics

let v= efflux vel. ; f=frictional force
using bernoulli's theorem ,
considering area of base of cyliner >> area of hole ,

ρgh = 12ρv²

v²=2gh

now force acting on cylinder due to liquid , F = dpdt = dmdt.v

now dmdt = ρ.dVdt = ρvs

thus Net Force acting on cylinder = ρsv² -f

now f = μ.N = shV*ρVg = ρsgh

F_net = 2ρsgh - ρsgh = ρsgh

accn = ρsghρV= sghV= μg

its clear now... thanks.