{ "metadata": { "name": "chapter13.ipynb" }, "nbformat": 3, "nbformat_minor": 0, "worksheets": [ { "cells": [ { "cell_type": "heading", "level": 1, "metadata": {}, "source": [ "Chapter 13: Dynamics of a Particle" ] }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 13.13-1, Page No 230" ] }, { "cell_type": "code", "collapsed": false, "input": [ "import math\n", "\n", "#Initilization of variables\n", "W=2 #lb\n", "F=1.5 #lb\n", "g=32.2 #ft/s**2\n", "\n", "#Angles are with respect to the plane are,\n", "# theta1=10 degrees & theta2=30 degrees\n", "sintheta1=0.17\n", "costheta1=0.99\n", "sintheta2=0.5\n", "costheta2=sqrt(3)*2**-1\n", "\n", "#Calculations\n", "#Now here the forces are considered as parallel and perpendicular to the plane \n", "#Applying Newtond Principle\n", "ax=(g/2)*(F*costheta1-(W*sintheta2)) #ft/s**2\n", "N1=(2*costheta2-(F*sintheta1)) #lb\n", "\n", "#result\n", "print'The force on the particle is',round(N1,2),\"lb\"\n", "print'The acceleration is',round(ax,2),\"ft/s**2\"\n", "\n", "# The answer may wary due to decimal point descrepancy." ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The force on the particle is 1.48 lb\n", "The acceleration is 7.81 ft/s**2\n" ] } ], "prompt_number": 2 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 13.13-2, Page No 231" ] }, { "cell_type": "code", "collapsed": false, "input": [ "import math\n", "\n", "#Initilization of variables\n", "m=5 #kg\n", "s=12 #m\n", "v=4 #m/s\n", "vo=0 #m/s\n", "g=9.8 #m/s**2\n", "mu=0.25\n", "\n", "#Calculations\n", "#Using the kinematic equations of motion\n", "a=(v**2-vo**2)*(2*s)**-1 #m/s**2\n", "#Using Newtons Principle\n", "N1=g*m #N\n", "P=m*a+mu*N1 #N\n", "\n", "#Result\n", "print'The value of P is',round(P,1),\"N\"\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The value of P is 15.6 N\n" ] } ], "prompt_number": 9 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 13.13-3, Page No 232" ] }, { "cell_type": "code", "collapsed": false, "input": [ "import math\n", "\n", "#Initilization of variables\n", "m=2 #kg\n", "vo=0 #m/s\n", "v=3 #m/s\n", "s=0.8 #m\n", "# as theta=20 degrees,\n", "sintheta=0.34\n", "costheta=0.94\n", "g=9.8 #m/s**2\n", "\n", "#Calculations\n", "N=m*g*costheta #N\n", "a=(vo**2-v**2)*(2*s)**-1 #m/s**2\n", "u=-((2*a)+(m*g*sintheta))/N \n", "#Solving for return speed\n", "#Symbol convention is different from textbook\n", "a_ret=((m*g*sintheta)-(u*N))/2 #m/s**2\n", "vf=sqrt((2*a_ret*s)) #m/s\n", "\n", "#Result\n", "print'The speed is',round(vf,1),\"m/s\"\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The speed is 1.3 m/s\n" ] } ], "prompt_number": 11 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 13.13-4, Page No 232" ] }, { "cell_type": "code", "collapsed": false, "input": [ "import math\n", "\n", "#Initilization of variables\n", "W=1800 #lb\n", "r=2000 #ft\n", "v=58.7 #ft/s\n", "g=32.2 #ft/s**2\n", "\n", "#Calculations\n", "F=(W*v*v)/(g*r) #lb\n", "\n", "#Result\n", "print'The frictional force to be exerted is',round(F,1),\"lb\"\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The frictional force to be exerted is 96.3 lb\n" ] } ], "prompt_number": 13 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 13.13-7, Page No 234" ] }, { "cell_type": "code", "collapsed": false, "input": [ "import math\n", "import numpy as np\n", "\n", "# Initilization of variables\n", "W=10 #lb\n", "# as theta=30 degrees,\n", "sintheta=2**-1\n", "costheta=sqrt(3)*2**-1\n", "l=2 #ft\n", "w=10 #rev/min\n", "g=32.2 # ft/s**2\n", "\n", "# Calculations\n", "r=l*costheta # ft\n", "a_n=r*(((w*2*pi)/60)**2) #ft/s**2\n", "#Applying Newtons Principle\n", "#Solving by matrix method\n", "A=np.array([[costheta,-sintheta],[sintheta,costheta]]) \n", "B=np.array([[(W*a_n)/g],[W]]) \n", "C=np.linalg.solve(A,B) #lb\n", "\n", "#Result\n", "print'The value of T is',round(C[0],2),\"lb\"\n", "\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The value of T is 5.51 lb\n" ] } ], "prompt_number": 15 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 13.13-8, Page No 235" ] }, { "cell_type": "code", "collapsed": false, "input": [ "import math\n", "\n", "#Initilization of variables\n", "m=4 #lb\n", "v=6 #ft/s\n", "r=2 #ft\n", "# as theta1=40 degrees & theta2=20 degrees\n", "sintheta1=0.64\n", "costheta1=0.77\n", "sintheta2=0.34\n", "costheta2=0.94\n", "g=32.2 #ft/s**2\n", "\n", "#Calculations\n", "a_n=v**2/r #ft/s**2\n", "#Applying Newtons Principle\n", "Fi=(m*a_n)/g #lb\n", "#Solving by matrix method\n", "A=np.array([[costheta1,costheta2],[sintheta1,-sintheta2]])\n", "B=np.array([[m],[Fi]]) \n", "C=np.linalg.solve(A,B) #lb\n", "\n", "#Result\n", "print'The values are: T=',round(C[0],2),\"lb\",'and C=',round(C[1],2),\"lb\"\n", "\n", "# The ans for C waries due to decimal point descrepancy." ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The values are: T= 4.01 lb and C= 0.97 lb\n" ] } ], "prompt_number": 16 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 13.13-10, Page No 237" ] }, { "cell_type": "code", "collapsed": false, "input": [ "import math\n", "\n", "#Initilization of variables\n", "m1=2 #kg\n", "# as theta=20 degrees,\n", "sintheta=0.34\n", "m2=4 #kg\n", "t=4 #s\n", "g=9.8 #m/s**2\n", "vo=0 #m/s\n", "\n", "#Calculations\n", "#Applying Newtons Principle\n", "#Solving by matrix method\n", "A=np.array([[1,-2],[1,4]])\n", "B=np.array([[m1*g*sintheta],[m2*g]])\n", "C=np.linalg.solve(A,B)\n", "a=C[1] #m/s**2\n", "v=vo+a*t #m/s\n", "\n", "#Result\n", "print'The velocity of 4kg mass is',round(v,1),\"m/s\"\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The velocity of 4kg mass is 21.7 m/s\n" ] } ], "prompt_number": 18 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 13.13-11, Page No 237" ] }, { "cell_type": "code", "collapsed": false, "input": [ "import math\n", "\n", "#Initilization of variables\n", "m_A=20 #lb\n", "m_B=60 #lb\n", "u=0.3 #coefficient of friction\n", "t=4 #s\n", "# as theta1=30 degrees & theta2=60 degrees,\n", "sintheta1=2**-1\n", "costheta1=sqrt(3)*2**-1\n", "sintheta2=sqrt(3)*2**-1\n", "costheta2=2**-1\n", "g=32.2 #ft/s^2\n", "vo=0 #ft/s\n", "\n", "#Calculations\n", "N1=m_A*costheta1 #lb\n", "N2=m_B*costheta2 #lb\n", "#Solving for T and a using matrix method\n", "A=np.array([[1,-m_A/g],[-1,-m_B/g]])\n", "B=np.array([[(m_A*sintheta1+u*N1)],[(-m_B*sintheta2+u*N2)]]) \n", "C=np.linalg.solve(A,B)\n", "a=C[1] #ft/s**2\n", "v=vo+a*t #ft/s\n", "\n", "#Result\n", "print'The velocity is',round(v,1),\"ft/s\"\n", "\n", "# The ans in the textbook is incorrect." ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The velocity is 44.7 ft/s\n" ] } ], "prompt_number": 20 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 13.13-12, Page No 238" ] }, { "cell_type": "code", "collapsed": false, "input": [ "import math\n", "\n", "#Initilization of variables\n", "m_A=40 #kg\n", "m_B=15 #kg\n", "F=500 #N\n", "g=9.8 #m/s**2\n", "# as theta=30 degrees,\n", "sintheta=2**-1\n", "costheta=sqrt(3)*2**-1\n", "\n", "#Calculations\n", "m=m_A+m_B #kg\n", "a=(F-m*g*sintheta)/(m) #m/s**2\n", "#Summing forces parallel and perpendicular to the plane\n", "#Simplfying equation (1) and (2)\n", "Nb=m_B*g+(m_B*a*sintheta) #N\n", "#Substituting this in eq(1)\n", "u=-(m_B*g*costheta-(Nb*costheta))/(Nb*sintheta)\n", "\n", "#Result\n", "print'The value of u is',round(u,2)\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The value of u is 0.31\n" ] } ], "prompt_number": 26 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 13.13-13, Page No 239" ] }, { "cell_type": "code", "collapsed": false, "input": [ "import math\n", "\n", "#Initilization of variables\n", "P=70 #N\n", "m_A=16 #kg\n", "u_AH=0.25 #coefficient of friction between Block A and Horizontal Plane\n", "m_B=4 #kg\n", "u_BH=0.5 #coefficient of friction between Block B and Horizontal Plane\n", "# as theta=10 degrees,\n", "sintheta=0.17\n", "costheta=0.98\n", "g=9.8 #m/s**2\n", "\n", "#Calculations\n", "#Applying sum of forces to both the FBD's\n", "#Solving by matrix method \n", "A=np.array([[-costheta,-u_AH,-m_A,0],[-sintheta,1,0,0],[costheta,0,-m_B,-u_BH],[sintheta,0,0,1]]) \n", "B=np.array([[-P],[m_A*g],[0],[m_B*g]])\n", "C=np.linalg.solve(A,B) \n", "\n", "#Result\n", "print'The Value of T is',round(C[0],1),\"N\"\n", "\n", "# The ans waries due to decimal point descrepancy." ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The Value of T is 20.7 N\n" ] } ], "prompt_number": 28 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 13.13-14, Page No 239" ] }, { "cell_type": "code", "collapsed": false, "input": [ "import math\n", "\n", "#Initilization of variables\n", "# as theta=10 degrees\n", "sintheta=0.1736\n", "costheta=0.9848\n", "v=10 #ft/s\n", "v0=0 #ft/s\n", "u=3**-1 #coefficient of friction\n", "g=32.2 #ft/s**2\n", "\n", "#Calculations\n", "#Equations of motion for box are\n", "#Simplfying the equations by sybstitution\n", "a=((u*costheta)-(sintheta))*g #ft/s**2\n", "#Time calculations\n", "t=(v-v0)/a #s\n", "\n", "#Result\n", "print'The value of a is',round(a,2),\"ft/s**2\",'and the time required is',round(t),\"seconds\"\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The value of a is 4.98 ft/s**2 and the time required is 2.0 seconds\n" ] } ], "prompt_number": 35 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 13.13-15, Page No 240" ] }, { "cell_type": "code", "collapsed": false, "input": [ "import math\n", "\n", "#Initilization of variables\n", "g=9.8 #m/s**2\n", "\n", "#Calculations\n", "#Simplfying the equations we can solve for T2 and aA first to obtain the solution\n", "#Solving by matrix method\n", "A=np.array([[-1.5,-4],[-3.5,24]])\n", "B=np.array([[-4*g],[-24*g]])\n", "C=np.linalg.solve(A,B) \n", "T2=C[0] #N\n", "T1=T2/2 #N\n", "T3=T2/2 #N\n", "#Acceleration calculations\n", "a1=1*g-T1 #m/s**2\n", "a2=(2*g-T1)/2 #m/s**2\n", "a3=(3*g-T3)/3 #m/s**2\n", "a4=(4*g-T3)/4 #m/s**2\n", "#Tension in fixed cord\n", "T_f=2*T2 #N\n", "\n", "#Result\n", "print'The acceleration values are: a1=',round(a1),\"m/s**2 (up)\",',',round(a2,1),\"m/s**2 (down)\",',',round(a3,2),\"m/s**2 (down)\",',',round(a4,1),\"m/s**2 (down) respectively.\"\n", "print'The tension in the fixed cord is',round(T_f,1),\"N\"\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The acceleration values are: a1= -9.0 m/s**2 (up) , 0.4 m/s**2 (down) , 3.53 m/s**2 (down) , 5.1 m/s**2 (down) respectively.\n", "The tension in the fixed cord is 75.3 N\n" ] } ], "prompt_number": 39 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 13.13-16, Page No 241" ] }, { "cell_type": "code", "collapsed": false, "input": [ "import math\n", "\n", "#Initilization of variables\n", "m1=14 #kg\n", "m2=7 #kg\n", "# as theta=45 degrees,\n", "sintheta=sqrt(2)**-1\n", "costheta=sqrt(2)**-1\n", "u_1=4**-1 #coefficient of friction between mass 1 and plane\n", "u_2=3*8**-1 #coefficient of friction between mass 2 and plane\n", "g=9.8 #m/s**2\n", "\n", "#Calculations\n", "#The equations of motion for m1 are\n", "N1=m1*g*costheta #N\n", "F1=u_1*N1 #N\n", "#The equations of motion for m2 are\n", "N2=m2*g*costheta #N\n", "F2=u_2*N2 #N\n", "#Now to get T and a we solve using matrix method\n", "A=np.array([[-1,-m1],[1,-m2]])\n", "B=np.array([[-(m1*g*sintheta-F1)],[-(m2*g*sintheta-F2)]])\n", "C=np.linalg.solve(A,B)\n", "\n", "#Result\n", "print'The Value of T is',round(C[0]),\"N\"\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The Value of T is 4.0 N\n" ] } ], "prompt_number": 40 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 13.13-19, Page No 244" ] }, { "cell_type": "code", "collapsed": false, "input": [ "import math\n", "\n", "#Initilization of variables\n", "W=12 #oz\n", "k=2 #oz/in\n", "M=0.34 #kg\n", "K=22 #N/m\n", "g=32.2 #ft/s**2\n", "\n", "#Calculations\n", "#Part(a)\n", "a=(k*W*g)/16\n", "b=W*16**-1\n", "f=((2*pi)**-1)*((a/b)**0.5) #Hz for simplicity the numerator and denominator have been computed seperately as a and b\n", "#Part(b)\n", "F=((2*pi)**-1)*((K/M)**0.5) #Hz\n", "\n", "#Result\n", "print'The frequency in part (a) is',round(f,2),\"Hz\",'and in part(b) is',round(F,2),\"Hz\"\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The frequency in part (a) is 1.28 Hz and in part(b) is 1.28 Hz\n" ] } ], "prompt_number": 41 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 13.13-20, Page No 244" ] }, { "cell_type": "code", "collapsed": false, "input": [ "import math\n", "\n", "#As the entire question is theoritical\n", "#theta is directly computed \n", "theta=arccos(2*3**-1)*(180/pi) #degrees\n", "\n", "#result\n", "print'The value of theta is',round(theta,1),\"degrees\"\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The value of theta is 48.2 degrees\n" ] } ], "prompt_number": 43 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 13.13-28, Page No 254" ] }, { "cell_type": "code", "collapsed": false, "input": [ "import math\n", "\n", "#Initilization of variables\n", "G=6.658*(10**-8)**-1 #cm**3/g.s**2\n", "#Calculations\n", "G1=G*((3.281*10**2)/((2.205*32.2**-1)*10**4)) #ft**3/slug-s**2\n", "G2=G1 #ft**4/lb-s**4\n", "\n", "#Result\n", "print'The ans is',round(G2,2),\"ft**4/lb-s**4\"\n", "\n", "# The ans waries slightly due to decimal point descrepancy." ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The ans is 319004859.68 ft**4/lb-s**4\n" ] } ], "prompt_number": 51 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 13.13-29, Page No 254" ] }, { "cell_type": "code", "collapsed": false, "input": [ "import math\n", "\n", "#Initilization of variables\n", "#Modifying the value of C without vo**2 in it\n", "C=5000*5280\n", "G=3.43*10**-8 #Gravatational Constant\n", "M=4.09*10**23 #Mass of the Earth\n", "a=5.31*10**8\n", "#When the orbit is circular e=0\n", "vo1=(a)**0.5 #ft/s\n", "#When the orbit is parabolic e=1\n", "vo2=((C*a+G*M)/C)**0.5 #ft/s\n", "\n", "#Result\n", "print'The value of vo1=',round(vo1),\"ft/s\",'is smaller than vo2=',round(vo2),\"ft/s, hence the Satellite will enter a hyperbolic path and never return to earth.\"\n", "#Decimal accuracy causes discrepancy in answers\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The value of vo1= 23043.0 ft/s is smaller than vo2= 32594.0 ft/s, hence the Satellite will enter a hyperbolic path and never return to earth.\n" ] } ], "prompt_number": 53 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 13.13-30, Page No 255" ] }, { "cell_type": "code", "collapsed": false, "input": [ "import math\n", "\n", "#Initilization of variables\n", "r=3940+500 #mi\n", "phi=0 #degrees\n", "vo=36000 #ft/s\n", "C=4440*5280*vo\n", "G=3.43*10**-8\n", "M=4.09*10**23 #kg\n", "\n", "#Calculations\n", "e=((C*vo)/(G*M))-1\n", "\n", "#Result\n", "print'The value of e=',round(e,2),\",hence the path is Hyperbolic\"\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The value of e= 1.17 ,hence the path is Hyperbolic\n" ] } ], "prompt_number": 54 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 13.13-31, Page No 255" ] }, { "cell_type": "code", "collapsed": false, "input": [ "import math\n", "\n", "#Initilization of variables\n", "a=92.9*10**6 #mi\n", "G=3.43*10**-8\n", "T=365*24*3600 #s\n", "c=5280\n", "\n", "#Calculations\n", "M=(4*pi**2*a**3*c**3)/(G*T**2) #slugs\n", "\n", "#Result\n", "print'The mass of the sun is',round(M,1),\"slugs\"\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The mass of the sun is 1.36584467048e+29 slugs\n" ] } ], "prompt_number": 56 } ], "metadata": {} } ] }