MCQ
A uniform solid sphere of mass $m$ is being pulled on a horizontal surface with force $F$ parallel to the surface and applied at its top most point. If the acceleration of the cylinder is $a$ & it is rolling on the surface, the value of $F$ is 
  • A
    $ma$
  • B
    $\frac {3}{2}\ ma$
  • $\frac {7}{10}\ ma$
  • D
    $\frac {10}{7}\ ma$

Answer

Correct option: C.
$\frac {7}{10}\ ma$
c
Writting torque equation about an axis passing through $A,$ perpendicular to the plane of paper.

$\Rightarrow \mathrm{F} \times 2 \mathrm{R}=\left(\frac{2}{5} \mathrm{mR}^{2}+\mathrm{mR}^{2}\right) \times \infty$ $...(i)$

$\mathrm{a}=\mathrm{R} \propto$

$\Rightarrow \mathrm{F}=\frac{7}{10} \mathrm{ma}$

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