posted by jujubes .
A fresh water pond that is 14.7 m deep is contained on one side by a cliff. The water has eroded a nearly horizontal "tube" through a bed of limestone, which allows the water to emerge on the other side of the cliff. If the "tube" has a diameter of 4.07 cm, and is located 6.0 m below the surface of the pond, what is the frictional force between the "tube" wall and a rock that is blocking the exit?
b) When the rock is removed, what volume of water flows out of the "tube" in 2.90 hr?
for part a)
where d is the distance of the tube beneath the surface of the water, and area is the cross sectional area of the tube, and rho the density of water.
make sure to convert the units of the diameter into cm before subbing it into the equation!