A vertical pipe 30 m long and 25 mm diameter has its lower end open and flush wi
ID: 3895239 • Letter: A
Question
A vertical pipe 30 m long and 25 mm diameter has its lower end open and flush with the inner surface of the cover of a box which is 0.15 m high, square in plan view, each side being 0.6 m long. The bottom of the box is horizontal. If the box and pipe are completely filled with water calculate
(a) the hydrostatic force exerted on the bottom of the box,
(b) the force exerted on the floor upon which the box rests excluding the weight of the box and the pipe.
(c) Explain why (a) and (b) are different.
Explanation / Answer
the hydrostatic force exerted on the bottom of the box = wt of water in (pipe + box)
= wh((pi/4)d*d) + wh(a*a) where w = weight density of water = 9810N/m3
= (9810*30*(pi/4)*0.025*0.025) + (9810*0.15*0.6*0.6) = 674.26N