Introduction To Special Relativity And Space Science (By S.P. Singh)

CHAPTER NUMBER 4 : FRAME OF REFERNCE

EXAMPLE NUMBER 4.1 : (Page Number 176)

In [64]:
import math
   #Given that
F = [2.5,4.5,-5]    # F is a force vector act through origin
F_magnitude = math.sqrt ( 2.5**2 + 4.5**2 + (-5)**2)
theta1_x = (180 / pi ) * math.acos ( 2.5 / F_magnitude)
theta1_y = (180 / pi ) * math.acos ( 4.5 / F_magnitude)
theta1_z = (180 / pi ) * math.acos ( -5 / F_magnitude)
print "   Magnitude of force F is ",round(F_magnitude,4)," N"
print "   Angle made with X - axis is ",round(theta1_x,4)," degree"
print "   Angle made with Y - axis is ",round(theta1_y,4)," degree"
print "   Angle made with Z - axis is ",round(theta1_z,4)," degree"
   Magnitude of force F is  7.1764  N
   Angle made with X - axis is  69.6479  degree
   Angle made with Y - axis is  51.1924  degree
   Angle made with Z - axis is  134.2335  degree

EXAMPLE NUMBER 4.2a : (Page Number 176)

In [65]:
import math
   #Given that
r = [2,2,2*math.sqrt(2)]
r_magnitude = math.sqrt ( 2**2 + 2**2 + (2*math.sqrt(2))**2)
math.cos_x =  ( 2 / r_magnitude)
math.cos_y = ( 2 / r_magnitude)
math.cos_z = ( 2.8284 / r_magnitude)
print "   Directional math.comath.sine in X - axis is ",math.cos_x," " 
print "   Directional math.comath.sine in Y - axis is ",math.cos_y," "
print "   Directional math.comath.sine in Z - axis is ",math.cos_z," " 
   Directional math.comath.sine in X - axis is  0.5  
   Directional math.comath.sine in Y - axis is  0.5  
   Directional math.comath.sine in Z - axis is  0.7071  

EXAMPLE NUMBER 4.2b : (Page Number 176)

In [67]:
import math
   #Given that
r_xz = [2,2.8282]
r_xz = math.sqrt (2**2 + (2.8282)**2)
r_yz = math.sqrt (2**2 + (2.8282)**2)
print "   Projection of vector r in xz plane is ",round(r_xz,4),""
print "   projection of vector r in yz plane is ",round(r_yz,4),""
   Projection of vector r in xz plane is  3.4639 
   projection of vector r in yz plane is  3.4639 

EXAMPLE NUMBER 4.4 : (Page Number 177)

In [82]:
import math
   #Given that
v_w_x = 40 * math.cos(45 * pi / 180)    # x component of wind blow in miles/h
v_w_y = 40 * math.sin(45 * pi /180)    # y component of wind blow in miles/h
r_x = 200    # distance  of destination point in x direction in miles
r_y = 0    # distance  of destination point in y direction in miles
t = 40    # time taken by aeroplane to reach destination in minutes
print "Standard formula used is V = V1 + V2 + .....+ V_n   "
v_x = (r_x)/t *60    # x - component of velocity  required to reach destination in time in miles/h
v_y = r_y /t *60    # x - component of velocity  required to reach destination in time in miles/h 
v_p_x = v_x - v_w_x    # x component of aeroplane velocity in miles/h
v_p_y = v_y - v_w_y    # y component of aeroplane velocity in miles/h
print "Vector of velocity of pilot with respect to moving air is ",round(v_p_x,4)," +i ",round(v_p_y,4),"j miles/h   where i and j stands for east and north respectively "
Standard formula used is V = V1 + V2 + .....+ V_n   
Vector of velocity of pilot with respect to moving air is  271.7045  +i  -28.273 j miles/h   where i and j stands for east and north respectively 

EXAMPLE NUMBER 4.5 : (Page Number 178)

In [87]:
import math
   #Given that
R_e = 6.4e6    # radius of earth in m
T = 8.64e4    # time period of one rotation of earth
theta1_pole = 90    # angle between pole and rotational axis 
theta1_equator = 0    # angle between equator and rotational axis 
g_pole = 9.8    # gravitational acceleration at pole in m/s**2
print "Standard formula used is g1 = g - R_e*f**2*(math.cos(theta1))**2   "
f = 2 * pi / T    # rotational frequency of earth
g_equator = g_pole -  R_e * f**2
del_g = g_pole - g_equator
print "Difference in gravitational acceleration at pole and equator is ",round(del_g,4)," m/s^2 "
Standard formula used is g1 = g - R_e*f**2*(math.cos(theta1))**2   
Difference in gravitational acceleration at pole and equator is  0.0338  m/s^2 

EXAMPLE NUMBER 4.6 : (Page Number 178)

In [91]:
import math
   #Given that
R_e = 6.4e6    # radius of earth in m
theta1_pole = 90    # angle between pole and rotational axis 
theta1_equator = 0    # angle between equator and rotational axis 
g_pole = 10    # gravitational acceleration at pole in m/s**2
g_equator = 0    # gravitational acceleration at equator in m/s**2
print "Standard formula used is g1 = g - R_e*f**2*(math.cos(theta1))**2   "
f = math.sqrt (g_pole / R_e)
T = 2 * pi / f / 3.6e3
print "Angular velocity of Earth will be ",f," rad/s   Time period would be ",round(T,4)," hours"
 Standard formula used is g1 = g - R_e*f**2*(math.cos(theta1))**2   
Angular velocity of Earth will be  0.00125  rad/s   Time period would be  1.3956  hours

EXAMPLE NUMBER 4.7 : (Page Number 179)

In [93]:
import math
   #Given that
g_pole = 9.8    # gravitational acceleration at pole
m = 1    # mass of substance in kg
R_e = 6.4e6    # radius of earth in m
print "Standard formula used is   coriolis force = -2*m*f x v   "
g_equator = 0.75 *g_pole    # gravitational acceleration at equator in m/s**2
f = math.sqrt ((g_pole - g_equator)/ R_e)
print "Angular velocity of Earth will be ",round(f,4)," rad/s .  "
Standard formula used is   coriolis force = -2*m*f x v   
Angular velocity of Earth will be  0.0006  rad/s .  

EXAMPLE NUMBER 4.8 : (Page Number 180)

In [98]:
import math
   #Given that
m = 1    # mass of particle in kg
theta1 = 30    # latitude position in degree
v = 0.5    # velocity of particle in km/s in north direction
print "Standard formula used is coriolis Force = 2*mass*angular velocity X velocity "
f_x = -2*m*2*pi * v*1000*(-1)*math.sin(theta1*pi/180)/86400    # coriolis force in east direction
f_z = -2*m*2*pi * v*1000*math.cos(theta1*pi/180)/86400    # coriolis force in verticle direction
F = math.sqrt(f_x**2+f_z**2)
alpha1 = -(math.atan(f_z/f_x)) *180 /pi
print "Magnitude and direction  of coriolis force on particle are   ",round(F,4)," N and ",round(alpha1,4)," degree with east respectively"
Standard formula used is coriolis Force = 2*mass*angular velocity X velocity 
Magnitude and direction  of coriolis force on particle are    0.0727  N and  60.0456  degree with east respectively