A standing wave `y = A sin kx .cos omegat` is established in a string fixed at its ends.
(a) What is value of instantaneous power transfer at a cross section of the string when the string is passing through its mean position?
(b) What is value of instantaneous power transfer at a cross section of the string when the string is at its extreme position?
(c) At what frequency is the power transmitted through a cross section changing with time?

Answer

(a) Zero
(b) Zero
(c) `omega/pi`