When the dike sprang a leak, the little Dutch boy placed his finger in the hole to stop the flow. We can model the dike as a dam 20 m high and 100 km long on top of an ocean which is another 980 m deep, 100 km wide, and 100 km long. Let's say the hole is a square 0.01 m by 0.01 m located 1 m below the surface of the water.
Assume that viscosity is negligible. We have
Patm = 105 Pa, ρwater = 103 kg/m3, and g = 10 m/s2.
What would be the velocity of the stream if the little Dutch boy removed his finger from the hole?