Unformatted text preview: CIVIL 2 131 , Fluid Mechanics
Tutorial 11 : Buoyancy and stability of floating bodies
Covers week 1 1 lecture material
A 170 - kg granite rock ( P = 2700 kg/m?" ) is dropped into a lake . A man dives in and tries to lift
the rock . Determine how much force the man needs to apply to lift it from the bottom of the
lake . Do you think he can do it ?
( ans : rock weighs 107 kj under water )
The gate shown consists of one quarter of a circular
cylinder and is used to maintain a water depth of H .
That is , when the water depth exceeds H], the gate opens
slightly and lets the water flow under it . Find the mass
M of the gate per W into the page .
TO 5 ph = 4 + 4 - 1 ,
1 - 3 7
To what depth d will this rectangular block ( with density 0. 75 times that of water) float in the
two- liquid reservoir ?
( d = 2. 04 [ )
P = 0. 75 P water
SG = 1. 0
d = ?
SG = 1.21
A cylindrical block of wood of diameter d and length [ has a specific density of s . Establish
criteria for which it floats in the water vertically ? Does it float vertically ford = 0. 3 m and
[ = 1. 0 m and $ = 0. 76 ?
( 7 > 2 / 2( 1 - 5 ) s and hence it won't float )
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