Q46 / 107 · NTA Abhyas (JEE Main) 2020 · Physics · Oscillations

The time period of a physical pendulum about some pivot point is T. When we take another pivot point, opposite of the first one such that the centre of mass of the physical pendulum lies on the line joining these two pivot points, we obtain the same time period. If the two points are separated by a distance L, then the time period T is

  • Correct answer
    A
    2πLg
  • B
    πLg
  • C
    2πL2g
  • D
    π2Lg

Solution

T=2πIC+mx2mg x=2πIC+m(L-x)2mg (L-x)

ICx+mx=ICL-x+m(L-x)

ICL-2xx(L-x)=m(L-2x) IC=mx (L-x)

T=2πmxL-mx2+mx2mgx=2πLg

Hence, the correct answer is option: 'A'.

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