A wave travels on a light string.The equation of the wave is $Y = A \,\sin \,(kx - \omega t + 30^o)$.It is reflected from a heavy string tied to an end of the light string at $x = 0$. If $64\%$ of the incident energy is reflected the equation of the reflected wave is
A$Y = 0.8\, A \sin \,(kx -\omega t + 30^o + 180^o)$
B$Y = 0.8\, A \sin \,(kx + \omega t + 30^o + 180^o)$
C$Y = 0.8\, A \sin \,(kx + \omega t -30^o)$
D$Y = 0.8\, A \sin \,(kx + \omega t + 30^o)$
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C$Y = 0.8\, A \sin \,(kx + \omega t -30^o)$
c $ y =.8 A \sin \left(-k x-\omega t+30^{\circ}+180^{\circ}\right) $
$=-.8 A \sin \left(-k x-\omega t+30^{\circ}\right) $
$=0.8 A \sin \left(k x+\omega t-30^{\circ}\right)$
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