【单选题】A wave traveling along a string is described by y ( x , t ) = 0.00327sin(72.1 x - 2.72 t ), in which the numerical constant are in SI units. What are the amplitude y m , angular wave number k , and th...
【简答题】Read this part of a letter Dear Sir or Madam Our Order Number 8044P On 13 May, we ordered six packs of A4 photocopy paper and one bottle of printer's ink from you. When we received this order, we foun...