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The x and y displacements of a particle are x(t)=a sin ω t and y(t)=a sin 2ω t. Its trajectory will look like

Asked in JEE Main Online 2015 · Lissajous figures

Figure: Lissajous figures
Answer: (3) a figure of eight lying on its side, crossing itself at the origin

Step-by-step solution

The frequency ratio is 2:1, which is the simplest Lissajous figure after the conics.

Using sin 2ω t=2 sin ω t cos ω t gives y=(2x)/a√a²-x², taking both signs of the root.

The curve passes through the origin twice, once going up and once going down, tracing a figure of eight lying on its side.

Why the other options are wrong

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