Consider a tube closed at one end and open at the other. A standing pressure wave is set up inside of that tube. By name or number, identify all of the four boundary conditions which must be satisfied to create this situation: 1) The absolute pressure at the open end of the pipe is zero 2) The gauge pressure at the open end of the pipe is zero 3) The gauge pressure at the closed end of the pipe is zero 4) The pressure at the closed end must equal the pressure at the open end