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Newton’s Laws of Motion — Physics STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 SciencePhysicsNewton’s Laws of Motion5 Marks
MCQ
Figure shows a heavy block kept on a frictionless surface and being pulled by two ropes of equal mass $m.$
 At $t = 0,$ the force on the left rope is withdrawn but the
force on the right end continues to act.
Let $F_1$ and $F_2$ be the magnitudes of the forces by the right rope and the left rope on the block respectively:
  • ✓
    $F_{1 }= F_2 = F$ for $t < 0.$
  • B
    $F_1 = F_2 = F + mg$ for $t < 0.$
  • C
    $F_1= F, F_2 = F$ for $t > 0.$
  • D
    $F_1< F, F_2 = F$ for $t > 0.$
✓

Answer

Correct option: A.
$F_{1 }= F_2 = F$ for $t < 0.$
At $t < 0,$ the block is in equilibrium in the horizontal direction.
So, $F_1= F_2 = F$
At $t > 0, F_2= 0$ and $F_1= F.$

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