{ "metadata": { "name": "", "signature": "sha256:da9a4303c6fc07c594d52c82662dd9ab6e23eae788f020d82b784ed3a6873663" }, "nbformat": 3, "nbformat_minor": 0, "worksheets": [ { "cells": [ { "cell_type": "heading", "level": 1, "metadata": {}, "source": [ "Chapter 4: The Conservation Law for Momentum" ] }, { "cell_type": "heading", "level": 3, "metadata": {}, "source": [ "ILLUSTRATIVE EXAMPLE 4.1, Page number: 39" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "\n", "#Variable declaration:\n", "Vx_in = 420 #Entry Velocity in X direction (m/s)\n", "Vx_out = 0 #Exit Velocity in X direction (m/s)\n", "Vy_in = 0 #Entry Velocity in Y direction (m/s)\n", "Vy_out = 420 #Exit Velocity in Y direction (m/s)\n", "m = 0.15 #Rate of water entrained by the steam (kg/s)\n", "lb = 1.0/4.46 #Pound force in a newton force\n", "\n", "#Calculations:\n", "Mx_out = m*Vx_out #Rate of change of momentum at entry in x-direction (kg.m)\n", "Mx_in = m*Vx_in #Rate of change of momentum at exit in x-direction (kg.m)\n", "My_out = m*Vy_out #Rate of change of momentum at entry in y-direction (kg.m)\n", "My_in = m*Vy_in #Rate of change of momentum at exit in y-direction (kg.m)\n", "Fxgc = (Mx_out - Mx_in)*lb #Force in X direction (lbf)\n", "Fygc = (My_out - My_in)*lb #Force in X direction (lbf)\n", "\n", "#Results:\n", "if Fxgc < 1:\n", " print \"The x-direction supporting force acting on the 90\u00b0 elbow is :\",round(-Fxgc,1),\" lbf acting toward the left. \"\n", "else:\n", " print \"The x-direction supporting force acting on the 90\u00b0 elbow is :\",round(Fxgc,1),\" lbf acting toward the right. \"\n", "if Fygc < 1:\n", " print \"The y-direction supporting force acting on the 90\u00b0 elbow is :\",round(-Fygc,1),\" lbf acting downwards. \" \n", "else:\n", " print \"The y-direction supporting force acting on the 90\u00b0 elbow is :\",round(Fygc,1),\" lbf acting upwards. \"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The x-direction supporting force acting on the 90\u00b0 elbow is : 14.1 lbf acting toward the left. \n", "The y-direction supporting force acting on the 90\u00b0 elbow is : 14.1 lbf acting upwards. \n" ] } ], "prompt_number": 6 }, { "cell_type": "heading", "level": 3, "metadata": {}, "source": [ "ILLUSTRATIVE EXAMPLE 4.2 Page number: 40" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "\n", "from math import sqrt,degrees,atan2\n", "\n", "#Variable declaration:\n", "Fx = -63 #Force component in X direction (N)\n", "Fy = 63 #Force component in Y direction (N)\n", "lbf = 0.22481 #Pound-forrce in unit newton (lbf)\n", "\n", "#Calculations:\n", "Fr = sqrt(Fx**2 + Fy**2)*lbf #The resultant supporting force (lbf)\n", "u = degrees(atan2(Fy,Fx)) #Angle between the positive x axis and the direction of the force (degrees)\n", "\n", "#Result: \n", "if (0