A solid sphere spinning about a horizontal axis with an angular velocity $\omega$ is placed on a horizontal surface. Subsequently it rolls without slipping with an angular velocity of

• A

  $2 \omega / 5$
• B

  $7 \omega / 5$
• Correct answer
  C

  $2 \omega / 7$
• D

  $\omega$

Solution

From cons. of anguler momentum about $\mathrm{A}$ $\Rightarrow v=\frac{2 R w}{7}$ $\Rightarrow W^{\prime}=\frac{2 w}{7}$

Hence, the correct answer is option: 'C'.