Question

The amplitude and time period in $SHM$ are $0.8 \, cm$ and $0.2 \, sec \, $ respectively. If the initial phase is $\pi / 2$ radian, then the equation representing $SHM$ is -

• A. $y=0.8cos 10 \pi t$
• B. $y=0.8sin \pi t$
• C. $y=3\times 0.8sin \pi t$
• D. $y=0.8sin 1 0 \pi t$

Answer 1

Answer: (A)

Use general equation of SHM
$y=asin \left(\omega t + \phi\right)$
$=0.8sin \left\{\frac{2 \pi t}{0.2} + \frac{\pi }{2}\right\}$
$=0.8sin \left(10 \pi \, t + \frac{\pi }{2}\right)$

$=0.8cos \, 10\pi t$