1.

A uniform sphere of mass m and radius R is placed on a rough horizontal surface. The sphere is struck horizontally at a heighth from the floor. Match the following:

Answer»

Solution : The SPHERE will roll without slipping if
`omega=(v)/(R)`
Moment of inertia about DIAMETER is
`I=(2)/(5)MR^(2)`
ANGULAR momentum of the sphere about C.M. is given by
`Mv(h-R)=I omega`
`=(2)/(5) MR^(2)*(v)/(R)`
or `mv(h-R)=(2)/(4) MvR`

or `h=(7)/(7)R`
So, if force is applied at `h = (7)/(5)R` sphere will roll without slipping
Torque DUE to sphere about `CM tau=F(h-R)`. sphere will have only translational motion if `t= 0 or h = R`. Sphere will spin clockwise if torque is positive and will spin anticlockwise if torque is negative.
So `(a) to (III), (b) to (iv), (c) to (ii), (d) to (i)`.


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