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4.1 , newtons laws of motion — Physics STD 11 Science — Question

Rajasthan BoardEnglish MediumSTD 11 SciencePhysics4.1 , newtons laws of motion1 Mark
MCQ
System shown in figure is in equilibrium and at rest. The spring and string are massless, now the string is cut. The acceleration of mass $2\,m$ and $m$ just after the string is cut will be
  • ✓
    $\frac {g}{2}$ upwards, $g$ downwards
  • B
    $g$ upwards, $\frac {g}{2}$ downwards
  • C
    $g$ upwards, $2g$ downwards
  • D
    $2g$ upwards, $g$ downwards
✓

Answer

Correct option: A.
$\frac {g}{2}$ upwards, $g$ downwards
a
$\mathrm{Kx}=3 \mathrm{mg}$

after cut the string

$a=\frac{F_{\text {ret }}}{2 m}=\frac{k x-2 m g}{2 m}$

$a=\frac{3 m g-2 m g}{2 m}=\frac{g}{2}$

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