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NTA Abhyas 2020
Exam
NTA Abhyas
Year
2020
Subject
Physics
Chapter
Center of Mass, Momentum and Collision

NTA Abhyas 2020 · Physics · Center of Mass, Momentum and Collision

Two particles A and B each of mass m are attached by a light...

Two particles AA and BB each of mass mm are attached by a light inextensible string of length 2l2l. The whole system lies on a smooth horizontal table with BB initially at a distance ll from AA. The particle at the end BB is projected across the table with speed uu perpendicular to ABAB. The velocity of the ball AA just after the string is taut, is

Two particles A and B each of mass m are attached by a light inextensible string of length 2l . The whole system lies

Options

  1. Au34\dfrac{u\sqrt{3}}{4}
  2. Bu3u\sqrt{3}
  3. Cu32\dfrac{u\sqrt{3}}{2}
  4. Du2\dfrac{u}{2}

Correct answer

A. u34\dfrac{u\sqrt{3}}{4}

Step-by-step solution

Two particles A and B each of mass m are attached by a light inextensible string of length 2l . The whole system lies

When the string jerk tight both particles begin to move with velocity components vv in the direction ABAB . Using conservation of momentum in the direction ABAB

mucos30°=mv+mvmucos 30 ° = mv + mv

or v=u34v = \dfrac{u\sqrt{3}}{4}

Hence, the velocity of ball AA just after the jerk is u34\dfrac{u\sqrt{3}}{4}
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