A point particle of mass 200 gram is executing S.H.M. of amplitude 0.2 m . When the particle passes through…

A point particle of mass 200 gram is executing S.H.M. of amplitude 0.2 m . When the particle passes through the mean position, its kinetic energy is $16 \times 10^{-3} \mathrm{~J}$. The equation of motion of this particle is (Initial phase of oscillation $=0^{\circ}$ )
  1. $Y=0.2 \sin (4 t)$
  2. $Y=0.2 \sin \left(\frac{t}{4}\right)$
  3. $Y=0.2 \sin \left(\frac{t}{2}\right)$
  4. $Y=0.2 \sin (2 t)$

Solution

Maximum kinetic energy in SHM relates to amplitude and angular frequency through the equation $KE_{\text{max}} = \frac{1}{2} m (A\omega)^2$.

Substituting known values $m = 0.2\ \text{kg}$, $A = 0.2\ \text{m}$, and $KE_{\text{max}} = 16 \times 10^{-3}\ \text{J}$:

$16 \times 10^{-3} = \frac{1}{2} (0.2) (0.2\omega)^2$

Solving for $\omega^2$:

$\omega^2 = \frac{16 \times 10^{-3}}{0.1 \times 0.04} = 4$

Thus $\omega = 2\ \text{rad/s}$.

The displacement equation becomes $Y = 0.2 \sin(2t)$, which corresponds to option D.

Asked in: MHT CET 2025 (05 May Shift 2)

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