Please help. I am desperate A string with both ends held fixed in vibrating in its third harmonic. The waves have a speed of 186m/s and a frequency of 250Hz. the amplitude of the standing wave at an antinode is 0.450cm. A. Calculate the amplitude at point on the string a distance of 15.0 cm fromthe left-hand end of the string B. How much time does it take the string to go from its largest upward displacement to its largest downward displacement at this point? C. Calculate the maximum transverse velocity of the string at this point. D. Calculate the maximum transver acceleration of the string at this point For this problem, I know how to derive frequency, angular frequency, wavelength, length of the string, etc. but I don't know how to use these info. to solve the problem. I just need something to start with. I have no idea how to start the problem. Thank alot.