堵塞物受到水的压强：p= F S = 24.5N 10×10?4m2 =2.45×104Pa；由p=ρgh得：洞口在水下的深度h= p ρg = 2.45×104Pa 1×103kg/m3×10N/kg =2.45m．答：洞口在水下的深度为2.45m．
