Practicing Success
A particle is projected along a horizontal field whose coefficient of friction varies as \(mu = \frac{A}{r^2}\), where r is the distance from the origin in meters and A is a positive constant. The initial distance of the particle is 1 m from the origin and its velocity is radially outwards. The minimum initial velocity at this point so the particle never stops is : |
\(2 \sqrt{gA}\) \(\sqrt{2gA}\) \(4 \sqrt{gA}\) \(\infty\) |
\(\sqrt{2gA}\) |
Work done against friction is equivalent to the kinetic energy of the body : \(\frac{1}{2}mv^2 = \int_1^{\infty} \mu .m. g .dr\) \(\frac{v^2}{2} = \int_1^{\infty} \frac{A}{r^2} g dx\) = \(-Ag\frac{1}{r}]_1^{\infty}\) \(\Rightarrow v^2 = 2 Ag\) \(\Rightarrow v = \sqrt{2Ag}\) |