The equation of a wave is given by
`y=10sin((2pi)/(45)t+alpha)`
If the displacement is 5 cm at t=0 ,then the total phase at t=7.5 sec is

Options

A. `(pi)/(3)`
B. `(pi)/(2)`
C. `(pi)/(6)`
D. `pi`

Answer

B

Explanation

The given equation of a wave is
y=10 `sin((2pi)/(45)t+alpha)`
At t=0,y=5 cm
`therefore 5=10sinalpha`
`(1)/(2)=sinalpha`
`sin((pi)/(6))=sinalpha`
`alpha=(pi)/(6)`
Hence ,the total phase at t=7.5 s(=`(15)/(2)`S) is
`phi=(2pi)/(45)xx(15)/(2)+alpha=(pi)/(3)+(pi)/(6)` (Using (i))
`=(3pi)/(6)=(pi)/(2)`