A string of length L fixed at both ends vibrates in its fundamental mode at a frequency v and a maximum amplitude A. (A) Find the wavelength and the wave number k. (B) Take the origin at one end of the string and the X-axis along the string. Take the Y-axis along The direction of the displacement. Take t = 0 at the instant when the middle point of the string passes through its mean position and is going towards the positive y-direction. Write the equation describing the standing wave.