Question

A box of mass 10 Kg, moves in circular motion with the mass function as m = 7t. The function for the radius is r = 2t^2. By what factor does the centripetal force exceed the square of the tangential velocity at t = 2 s?

(a) 7/4

(b) 7/5

(c) 7/2

(d) 7

I had been asked this question in an international level competition.

Question is taken from Non-Uniform Circular Motion topic in section Laws of Motion of Physics – Class 11

Answer 1

Correct choice is (a) 7/4

For explanation: The centripetal force on a body is given as Fc = mv^2/r. Hence, the required factor is the ratio of the mass to the radius at t = 2s. Hence, required factor = m/r = 7/2t. On substituting the values, we get the factor as 7/4.