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During the propagation of one progressive harmonic wave having amplitude 10 m, displacements and particles at 2 m and 16 m at respectively 2s and 8 s are5 mand 5sqrt3 m respectively. Find angular frequency and wave vector for this wave. |
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Answer» SOLUTION :`(i) y _(1) = A sin (omega t _(1) - kx _(1))` `therefore 5 = 10 sin (2 omega -2k)` `therefore sin (2 omega -2k) =1/2 = sin ""(pi)/(6)` `therefore 2 omega - 2k = (pi)/(6)` `therefore 12 omega - 12k =pi ""...(1)` `(ii) y _(2) = A sin (omega t _(2) - kx _(2))` `therefore 5 sqrt3 = 10 sin (8 omega -16K)` `therefore sin (8 omega - 16k ) = (sqrt3)/( 2) = sin ""(pi)/(3)` `therefore 8 omega - 16 K = (pi)/(3)` `therefore 24 omega - 48 k =pi ""...(2)` Multiplying equation (1) by `(-2)` we GET, `-24 omega + 24 k =- 2pi` Adding equation (2) and (3), `- 24 k =- pi` `therefore k = (pi)/(24) (rad)/(m) ""...(4),` From (1) and (4), `12 omega -12 ((pi)/(24)) = pi` `therefore 12 omega -(pi)/(2) =pi` `therefore 12 omega = (3pi)/(2)` `therefore omega = (pi)/(8) (rad)/(s) ""...(5)` |
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