Q95 / 120 · JEE Advanced 2006 · Physics

A solid sphere is in pure rolling motion on an inclined surface having inclination $\theta$. Figure

  • A
    frictional force acting on sphere is $f=\mu m g \cos \theta$
  • B
    $f$ is disspative force
  • Correct answer
    C
    friction will increase its angular velocity and decreases its linear velocity
  • Correct answer
    D
    If $\theta$ decreases, friction will decrease

Solution

In case of pure rolling, $$ \begin{aligned} & f=\frac{m g \sin \theta}{1+\frac{m R^2}{I}} \\ \therefore & f \propto \sin \theta \end{aligned} $$ (upwards) Therefore, as $\theta$ decreases force of friction will also decrease.

Hence, the correct answer is options: 'C', 'D'.

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