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Question: Answered & Verified by Expert
A particle moves with simple harmonic motion in a straight line. In first τ s , after starting from rest it travels a distance a, and in next τ s  it travels 2a, in same direction, then :
PhysicsOscillationsJEE MainJEE Main 2014 (06 Apr)
Options:
  • A Amplitude of motion is 3a
  • B Time period of oscillations is 8 τ
  • C Amplitude of motion is 4a
  • D Time period of oscillations is 6 τ
Solution:
2492 Upvotes Verified Answer
The correct answer is: Time period of oscillations is 6 τ
           x = - A cos ω t

- A + a = - A cos ω τ                ...(i)

- A + 3 a = - A cos ω 2 τ          ...(ii)

∴    - 1 + a A = - cos ω τ              ...(iii)

and - 1 + 3 a A = - cos 2 ω τ           ...(iv)

Adding (iii) and (iv)

2 = 3  cos ω τ - 2  cos 2 ω τ + 1

∴    2  cos 2 ω τ - 3  cos ω τ + 1 = 0

∴    cos ω τ = 1 2

∴        ω τ = π 3

∴         T = 6 τ

 

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