question_answer

The radius of circle, the period of revolution, initial position and sense of revolution are indicated in the fig.

[NEET 2019]

Y-projection of the radius vector of rotating particle P is:

A) \[(y)t=3cos\left( \frac{3\pi t}{2} \right)\], where y in m

B)  \[(y)t=3cos\left( \frac{\pi t}{2} \right)\], where y in m

C)  \[(y)t=-3cos2\pi t\], where y in m

D)  \[(y)t=4\sin \left( \frac{\pi t}{2} \right)\], where y in m

Correct Answer: B

Solution :

[b]

\[y=r\text{ }cos\theta \]

\[y=3\text{ }cos\omega t\]

\[y=3\text{ }cos\frac{2\pi }{4}.t\]

\[y=3\text{ }cos\frac{2\pi }{2}\]