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JEE Main 2022 (24 Jun, Shift 1) · Torque, Couple & Equilibrium of Rigid Bodies

Torque, Couple & Equilibrium of Rigid Bodies question from JEE Main 2022 (24 Jun, Shift 1)

Q20JEE Main 2022 · 24 JUN · SHIFT 1Medium

Torque, Couple & Equilibrium of Rigid Bodies

A metre scale is balanced on a knife edge at its centre. When two coins, each of mass 10 g are put one on the top of the other at the 10.0 cm mark the scale is found to be balanced at 40.0 cm mark. The mass of the metre scale is found to be x ×\times 10−-2 kg. The value of x is ___________.

Numerical answer type. Work it out, then open the answer.

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Answer: 6

  1. The scale's weight acts at 50 cm; the new balance point is 40 cm.
  2. Coins: 2020 g at 10 cm, arm =30= 30 cm. Scale: mass MM at 50 cm, arm =10= 10 cm.
  3. 20×30=M×10⇒M=6020 \times 30 = M \times 10 \Rightarrow M = 60 g =6×10−2= 6 \times 10^{-2} kg
  4. So x=6x = 6.
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