1.

In a standing wave experiment , a 1.2 - kg horizontal rope is fixed in place at its two ends ( x = 0 and x = 2.0 m) and made to oscillate up and down in the fundamental mode , at frequency of 5.0 Hz. At t = 0 , the point at x = 1.0 m has zero displacement and is moving upward in the positive direction of y - axis with a transverse velocity 3.14 m//s. What is the correct expression of the standing wave equation ?

Answer»

`(0.1) sin ( pi//2) x sin (10 pi) t`
`(0.1) sin (pi) x sin (10 pi) t`
`(0.05) sin (pi//2) x cos (10 pi) t`
`(0.04) sin (pi//2) x sin (10 pi) t`

Solution :`mu = (1.2)/(2) = 0.6 kg//m`
`N = 5 Hz`
`lambda = 2 l = 4 m`
`V = n lambda = 5 XX 4 = 20 m//s`
Using `v = sqrt((T)/(mu))`
`T = 20^(2) xx 0.6 = 240 N`
`((delta y)/( delta t))_(max) = 3.14 m//s`
`( 2 A)omega = 3.14`
Amplitude `2A = (3.14)/(2 xx (3.14) xx 5) = 0.1 m`
EQUATION of standing wave is
`y = (0.1) sin (pi)/(2) s sin (10 pi) t`


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