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Oscillations

Question
CBSEENPH11020860

A particular of mass m is executing oscillation about the origin on X- axis. Its potential energy is V(x) = K |x|3. Where K is a positive constant. If the amplitude of oscillation is a, then its time period T is proportional to

  • 1a

  • a

  • a

  • a3/2

Solution

A.

1a

Given, V = kx3

Total energy (E) = Maximum potential energy

= ka3

From conservation of energy

12 m dxdt2 + kx2 = ka3 12m dxdt2 = k(a3 -x3) dxdt = 2km(a3-x3)dxa3-x3 = 2kmdtOr integrating0a dxa3 - x3 = 2km0T/4dtor 0a dxa3-x3 = 2kmT4Let x = a sin θ  dx = a cos θ  0π/2 a cos θ a3 -(a sin θ)3 = 2Km T4