Answer Happy

1) A 0.39-kg block on a horizontal frictionless surface is attached to an ideal spring whose force constant (spring constant) is 570 N/m. The block is pulled from its equilibrium position at x = 0.000 m to a displacement x = +0.080 m and is released from rest. The block then executes simple harmonic motion along the horizontal x-axis. When the position of the block is x = 0.057 m, its kinetic energy is closest to E) 0.95 J. A) 0.90 J. B) 1.0 J. C) 0.84 J. D) 1.1 J. 2) Four waves are described by the following equations, where distances are measured in meters and times in seconds. I. y = 0.12 cos(3x - 21t) II. y = 0.15 sin(6x + 42t) III. y = 0.13 cos(6x + 21t) IV. y = -0.23 sin(3.x - 42t) Which of these waves have the same speed? A) II and III B) II and IV C) III and IV D) I and III E) I and II 3) An ideal fluid flows at 12 m/s in a horizontal pipe. If the pipe narrows to half its original radius, what is the flow speed in the narrower section? A) 36 m/s B) 12 m/s C) 24 m/s D) 48 m/s 4) A mass of 1000 kg hangs at the end of a steel rod 5.0 m in length. The diameter of the rod is 0.80 cm and Young's modulus for the rod is 210,000 MN/m2. What is the elongation of the rod? A) 1.2 cm B) 0.46 cm C) 1.8 cm D) 0.047 cm E) 0.12 cm