(a) Determine the speed of longitudinal waves in a rectangular piece of copper with length: 140 x 103 m width: 2.21x 104 mm, and height: 1l1x 103 cm_ The peice of copper has a mass of 1.33 x 109 Kg and an elastic modulus of 117 Gpa: (b) How long will it take a pulse to travel across the piece of copper and return to its original point?