1.

The centripetal force F acting on particle moving uniformly in a circle may depend upon mass (m), velocity (v) and radius (r) of the circle. Derive the formula for F using the method of dimensions.

Answer»

Let F = K ma vb rc

Where K is the dimensionless constant of proportionality and a, b, c are the powers of m, v and r respectively to represent F.

Writing the dimensions of various quantities in equation (ii), we get

[M1L1T-2] = [M]a [LT-1]b [L]c

= Ma Lb T-b Lc = Ma Lb + T-b

Applying the principle of homogeneity of dimensions we get

a = 1, b +c = 1

-b = -2 or, b = 2

From (ii) c = 1 -b = 1 -2 = -1

Putting the values of a,b and c, in (i) we get

F = K m1 v2 r-1

or, F =K mv2/r



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