Answer the following questions in the space provided. Please be sure to writecomplete answers. (each question carries 2 marks, except for questions 11 - 13, which carry 1 mark each) For questions 11-13, refer to diagram below in which a standing wave is established on a 4.0 m long string : (K/U) 11. The number of nodes are : (K/U) 12. The wavelength is:(K/U) 13. If the frequency of vibration is 80 Hz, the speed of the wave in the wire is: (A)