Q. The equation of a wave is given by y=$10\sin\left( \frac{2\pi}{45}t + a \right)$. If the displacement is 5 cm at t=0, then the total phase at t=7.5s is
A) $\pi$
B) $\frac{\pi}{6}$
C) $\frac{\pi}{2}$
D) $\frac{\pi}{3}$
Explanation
(d) $Y = 10\sin\left\lbrack \frac{2\pi}{45}t + a \right\rbrack$
If t=0, y=5 cm
5=10(sin a)
$\sin{a = \frac{1}{2}}$
$a = \frac{\pi}{6}$
If t=7.5 g
Then total phase =
$\frac{2\pi}{45} \times \frac{15}{2} + \frac{\pi}{6} = \frac{\pi}{3} + \frac{\pi}{6} = \frac{\pi}{2}\ $
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.