Question:
A pulley fixed to the ceiling carries a string with blocks of masses $m$ and $3m$ attached to its ends. The masses of string and pulley are negligible. When the system is released, the acceleration of centre of mass will be
A pulley fixed to the ceiling carries a string with blocks of masses $m$ and $3m$ attached to its ends. The masses of string and pulley are negligible. When the system is released, the acceleration of centre of mass will be
Updated On: Jun 20, 2022
- zero
- $-\frac {g}{4} $
- $\frac {g}{2} $
- $-\frac {g}{2} $
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The Correct Option is B
Solution and Explanation
Let T be the tension in the string carrying the masses m and 3m.
Let a be the acceleration, then
$\hspace10mm $ T-mg=ma $\hspace5mm $ ...(i)
$\hspace10mm $ 3mg-T=3ma $\hspace5mm ...(ii) $
$\hspace10mm $ 2mg=4ma
$\Rightarrow \hspace10mm a= \frac {g}{2} $
$a_{cm} = -g/4$
Let a be the acceleration, then
$\hspace10mm $ T-mg=ma $\hspace5mm $ ...(i)
$\hspace10mm $ 3mg-T=3ma $\hspace5mm ...(ii) $
$\hspace10mm $ 2mg=4ma
$\Rightarrow \hspace10mm a= \frac {g}{2} $
$a_{cm} = -g/4$
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