Verified Solution • 2025–26 Session moderate

QJEEM18Ph4014: JEE Main 2018 Physics - Class 11 JEEM18Ph4014 Solution: A particle is moving with a uniform speed in a circular orbit…

A particle is moving with a uniform speed in a circular orbit of radius R in a central force inversely proportional to the nth power of R. If the period of rotation of the particle is T, then :

Multiple Choice Options

  • A T ∝ Rn/2
  • B T ∝ R3/2 for any n
  • C T ∝ Rn/2 +1
  • D T ∝ R(n+1)/2

Step-by-Step Verified Solution

We know, Central force in circular motion, F = mω2R

According to the question,

F∝1Rn

∴ mω2R ∝1Rn

⇒mω2R=kRn

⇒ω2=kmRn+1

∴ ω∝1Rn+12 .......(1)

And we know, T=2πω

∴ T∝1ω ...... (2)

From (1) and (2) we can conclude that,

T∝Rn+12

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