A wave in a string has an amplitude of `2 cm`. The wave travels in the `+ve` direction of x axis with a speed of 1`28 ms^-1` and it is noted that `5` complete waves fit in `4 m` length of the string. The equation describing the wave is

Options

A. y = (0.02) m sin (7.85 x + 1005t)
B. y = (0.02) m sin (15.7 x - 2010t)
C. y = (0.02) m sin (15.7 x + 2010t)
D. y = (0.02) m sin (7.85 x - 1005t)

Answer

D

Explanation

`5lambda=4implieslambda=0.8m`
`f=(v)/(lambda)=(128)/(0.8)=160Hz`
`omega=2pif=1005rad//s`
also `k=(2pi)/(lambda)=(2pi)/(0.8)=7.85m^(-1)`
`y=(0.02)msin(kx-omegat)`
`=(0.02)msin(7.85x-1005t)`.