일반물리학 1 — Fluids: Problem 2

2 In Fig. 14-21, the fresh water behind a reservoir dam has depth $D = 12 \text{ m}$. A horizontal pipe $4.0 \text{ cm}$ in diameter passes through the dam at depth $d = 6.0 \text{ m}$. A plug secures the pipe opening. (a) Find the magnitude of the frictional force between plug and pipe wall. (b) The plug is removed. What water volume exits the pipe in $3.0 \text{ h}$?