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Question: Answered & Verified by Expert
Two masses A and B connected with an inextensible string of length l lie on a smooth horizontal plane. A is given a velocity of v m s-1 along the ground perpendicular to line AB as shown in the figure. Find the tension in a string during their subsequence motion.

PhysicsCenter of Mass Momentum and CollisionNEET
Options:
  • A 2mv23l
     
  • B 3mv22l
  • C mv22l
  • D 4mv23l
Solution:
1918 Upvotes Verified Answer
The correct answer is: 2mv23l
 
From conservation of linear momentum

v cm = m × 0 + 2mv m + 2m v cm = 2v 3

position of the centre of mass

ycm=0×2m+m×l2mycm=l3



blocks will perform circular motion in the center of mass frame

velocity of A in COM frame is v A = v - 2 v/3 v A = v/3

Tension will provide the required centripetal force

T = 2m v A 2 / 3 T = 2m v/3 2 / 3 T = 2mv 2 3

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