A particle moves in $x-y$ plane according to rule $\mathrm{x}=\mathrm{a} \sin \omega \mathrm{t}$ and…

A particle moves in $x-y$ plane according to rule $\mathrm{x}=\mathrm{a} \sin \omega \mathrm{t}$ and $\mathrm{y}=\mathrm{a} \cos \omega \mathrm{t}$. The particle follows
  1. an elliptical path
  2. a circular path
  3. a parabolic path
  4. a straight line path inclined equally to $x$ and $y$-axes

Solution

$\begin{aligned} & \mathrm{x}=\mathrm{a} \sin \omega \mathrm{t} \Rightarrow \frac{\mathrm{x}}{\mathrm{a}}=\sin \omega \mathrm{t} \\ & \mathrm{x}=\mathrm{a} \cos \omega \mathrm{t} \Rightarrow \frac{\mathrm{x}}{\mathrm{a}}=\cos \omega \mathrm{t} \\ & \therefore \quad \frac{\mathrm{x}^2}{\mathrm{a}^2}+\frac{\mathrm{y}^2}{\mathrm{a}^2}=1 \\ & \text { or } \quad \mathrm{x}^2+\mathrm{y}^2=\mathrm{a}^2 \end{aligned}$ This is equation of circle, so the particle follows a circular path. .

Asked in: NEET 2010 (Mains)

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