Buoyant Formula and Sample Examples

Buoyant Formula :

Buoyant Formula is force acting Fb(N) in Newton is equal to the Force acting up wards F2(N)  in Newton and minus the force acting downwards F1(N) in Newton. Buoyant Formula can be written as

Fb(N)=F2(N)-F1(N)

Where,

F→ force acting in Newton

F2→ force acting upwards

F1→ force acting downwards

Force, F=PA

Where,

P→ pressure and

A→ Area

In terms of Area Height and volume, it is given by,

Fb=h2pg-h1pg

Where,

P→ density of the fluid is  p

g → gravity in Newton/Kg-1

V → volume of the immersed part of the body in the fluid in SI unit cube meter m3

h→ height of the immersed part  in cm

A→ area in m2

Sample Problems :

Example 1:

A block of wood with length =3.5m, width=0.3 and height=0.8m. The density of water

1000kg/m3  If the block is placed in the water, when is the buoyant force. Acceleration due to gravity is 20N/kg

Solution :

Known,

Volume of the block V=length*width*height=3.5*0. *0.8=0.84m3

Density of water (p)=1000kg/m3

Acceleration due gravity (g)=20N/kg

Formula of buoyant force

F=(1000)(20)(0.84)

F=16800Newton

Example 2:

A block of wood with length =4.5m, width=0.8 and height=10m. The density of water

100kg/m3  If the block is placed in the water, when is the buoyant force. Acceleration due to gravity is 10N/kg

Solution :

Known,

Volume of the block V=length*width*height=4.5*0.8*10=36m3

Density of water (p)=100kg/m3

Acceleration due gravity (g)=10N/kg

Formula of buoyant force

F=(100)(10)(36)

F=36000Newton

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