Assertion : A solid and a hollow sphere both of equal masses and radii are put on a rough surface after rotating with some angular velocity say `omega_(0)`. Coefficient of friction for both the spheres and ground is same. Solid sphere will start pure rolling first
Reason : Radius of gyration of hollow sphere about an axis passing through its centre of mass is more.

Options

A. If both Assertion and Reason are correct and Reason is the correct explanation of Assertion
B. If both Assertion and Reason are true but Reason is not the correct explanation of Assertion
C. If Assertion is true but Reason is fasle
D. If Assertion is false but Reason is true

Answer

A

Explanation

Pure rolling will start when

`v=R omega,mug t=R[omega_(0)-(mu_(0)gR)/(I)t]`
`:. t=(Romega_(0))/(mug+(mumR)/(I)), I_("solid") lt I_("hollow") :. t_("solid") lt t_("hollow")`.