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Oscillations

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Question 14
a.

For a simple harmonic oscillator, the potential energy EpE_pEp​ as a function of displacement xxx is given by the equation:

Ep=12mω2x2 E_p = \frac{1}{2} m \omega^2 x^2 Ep​=21​mω2x2

where mmm is the mass of the oscillator and ω\omegaω is its angular frequency. Show that this equation is homogeneous by reducing both sides to S.I. base units.

[3]
b.

A vertical cylindrical buoy of cross-sectional area A=0.035 m2A = 0.035\text{ m}^2A=0.035 m2 floats in seawater of density ρ=1020 kg m−3\rho = 1020\text{ kg m}^{-3}ρ=1020 kg m−3.

A weight of mass MMM is placed on top of the buoy, depressing it vertically by a distance x=15.0 cmx = 15.0\text{ cm}x=15.0 cm to a new equilibrium position. Calculate MMM.

[3]
c.

When the weight is suddenly removed, the buoy oscillates vertically with simple harmonic motion. The acceleration aaa of the buoy is given by the equation:

a=−ρgAmx a = -\frac{\rho g A}{m} x a=−mρgA​x

where mmm is the mass of the buoy, AAA is its cross-sectional area, ρ\rhoρ is the density of the seawater, ggg is the acceleration of free fall (9.81 m s−29.81\text{ m s}^{-2}9.81 m s−2), and xxx is the displacement from the equilibrium position.

For this buoy, m=12.5 kgm = 12.5\text{ kg}m=12.5 kg and A=0.035 m2A = 0.035\text{ m}^2A=0.035 m2. Show that the period TTT of the oscillations is approximately 1.2 s1.2\text{ s}1.2 s.

[4]

Oscillations Questions

  1. A Level
  2. /Physics
  3. /Oscillations