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Question: Answered & Verified by Expert
In a physical balance working on the principle of moments, when 5mg weight is placed on the left pan, the beam becomes horizontal. Both the empty pans of the balance are of equal mass. Which of the following statements is correct?
PhysicsRotational MotionJEE MainJEE Main 2017 (08 Apr Online)
Options:
  • A Every object that is weighed using this balance appears lighter than its actual weight
  • B Left arm is shorter than the right arm
  • C Both the arms are of same length
  • D Left arm is longer than the right arm
Solution:
2716 Upvotes Verified Answer
The correct answer is: Left arm is shorter than the right arm

Let m 1 and m 2 be the masses of pan

It is given that m1=m2



Since balance is achieved, so net torque about O should be zero.
5mg+ m 1 g r 1 = m 2 g r 2
5mg+m1gr1=m1gr2
r1r2=m1gm1g+5mg
r1r2<1

So, left arm is shorter than the right arm.

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