Question
Derive an expression for terminal velocity of a body of radius ‘r’ and weight W falling in a viscous media of coefficient of viscosity η.
Solution
Let 
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...(1)
Where k is constant of proportionality.
Substituting the dimension formula of each quantity in equation (1),
We get, 
Equating the powers of M, L and T on both the sides,
b + c = 0
a + b - c = 1
-2b - c = -1
On solving the above equations, we get
a = -1, b = 1, c = -1
Subsituting for a, b and c in (1), we get
This is the required expression for coefficient of viscosity.
