Air flows steadily between two sections in a long, straight portion of 10-cm inside diameter pipe. The uniformly distributed temperature and pressure at each section are given. The average air velocity at Sections (1) and (2) are 66 m/s and 300 m/s, respectively. Assume uniform velocity distributions. Determine the frictional force (Rx) exerted by the pipe wall on the airflow between the sections. At section (1), p1 = 7 MPa, T1 = 25°C, and V1 = 66 m/s. At section 2, p2 = 1.3 MPa, T1 = -20°C, and V2 = 300 m/s. (5 pt)