File:Centripetal force vs external force vectors.svg

Uploaded by Svebert
Upload date 2013-02-28T17:58:45Z
MIME type image/svg+xml
Dimensions 623 × 327 px
File size 233.6 KB

Summary

Description
English: Shows in the upper half the position of a valve of a wheel seen from the reference frame ”Street” -> Cycloid
  • In black the position in x-y plane
  • in red the instantaneous velocity of the valve
  • in green the inst. acceleration

Lower part: The decomposition of the external force (left side of newton 2)

  • Blue tangent component (tangent to the instantaneous circle of curvature) of this force
  • Yellow centripetal component
Date
Source Own work
Author Svebert
SVG development
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Source code
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Python code

############Script to produce this figure (python)##############
from math import *
import numpy as np
import matplotlib.pyplot as plt

tarr=np.linspace(-1.0,3*pi,400)
xarr=np.zeros(len(tarr))
yarr=np.zeros(len(tarr))
vxarr=np.zeros(len(tarr))
vyarr=np.zeros(len(tarr))
axarr=np.zeros(len(tarr))
ayarr=np.zeros(len(tarr))
apxarr=np.zeros(len(tarr))
apyarr=np.zeros(len(tarr))
aZpxarr=np.zeros(len(tarr))
aZpyarr=np.zeros(len(tarr))
aFZp=np.zeros(len(tarr))
aF=np.zeros(len(tarr))
i=0
R=2.0
r=R
omega=1.0
for t in tarr:
	xarr[i]=R*omega*t-r*sin(omega*t)
	yarr[i]=R-r*cos(omega*t)
	i+=1

vxarr=np.diff(xarr)
vyarr=np.diff(yarr)

axarr=np.diff(vxarr)
ayarr=np.diff(vyarr)

#Kruemmungsradius
#vsquared
for i in range(len(tarr)-2):
	v2=vxarr[i]*vxarr[i]+vyarr[i]*vyarr[i]
	av=vxarr[i]*axarr[i]+vyarr[i]*ayarr[i]
	apxarr[i]=av*vxarr[i]/v2
	apyarr[i]=av*vyarr[i]/v2
      	aZpxarr[i]=axarr[i]-apxarr[i]
      	aZpyarr[i]=ayarr[i]-apyarr[i]
	aF[i]=sqrt(axarr[i]*axarr[i]+ayarr[i]*ayarr[i])
	aFZp[i]=sqrt(aZpxarr[i]*aZpxarr[i]+aZpyarr[i]*aZpyarr[i])


plt.figure()

plt.subplot(211,aspect='equal',adjustable='box',title='Reference frame "Street": velocity and acceleration')
plt.plot(xarr,yarr,'k')
plt.hold(1)
plt.quiver(xarr[::20],yarr[::20],vxarr[::20],vyarr[::20],color='r',label='velocity')
plt.hold(1)
plt.quiver(xarr[::20],yarr[::20],axarr[::20],ayarr[::20],color='g',label='acceleration')
plt.ylim([0,max(yarr)])
plt.xlim([0,max(xarr)])

#plt.axes().set_aspect('equal')
#pl.show()
#plt.axes().set_aspect('equal')
plt.subplot(212,aspect='equal',adjustable='box',title='Reference frame "Street": Tangent and Centripetal Force')
#plt.figure()
plt.plot(xarr,yarr,'k')
plt.hold(1)
plt.quiver(xarr[::20],yarr[::20],apxarr[::20],apyarr[::20],color='b')
plt.quiver(xarr[::20],yarr[::20],aZpxarr[::20],aZpyarr[::20],color='y')
plt.ylim([0,max(yarr)])
plt.xlim([0,max(xarr)])
plt.savefig('centripetal_force_vs_external_force_vectors.svg')
#plt.axes().set_aspect('equal')

#plt.show()
plt.figure()
plt.title("External Force, tangent and centripetal components")
plt.plot(axarr,ayarr,'g', label='External Force')
plt.hold(1)
plt.plot(aZpxarr,aZpyarr,'y.', label='Centripetal Force')
plt.plot(apxarr,apyarr,'b.',label='Tangent Force')
plt.ylim([min(min(ayarr),min(aZpyarr),min(apyarr)),max(max(ayarr),max(aZpyarr),max(apyarr))*1.6])
plt.legend()
plt.axes().set_aspect('equal')
plt.savefig('centripetal_force_vs_external_force_circles.svg')

plt.figure()
plt.title('External Force and centripetal component vs. time')
plt.hold(1)
plt.plot(tarr,aFZp,'y',label='centripetal component')
plt.plot(tarr,aF,'g',label='External Force')
plt.legend(loc='lower left')
plt.xlim([0,tarr[len(tarr)-3]])
plt.savefig('centripetal_force_vs_external_force_time_series.svg')
#plt.show()

Licensing

I, the copyright holder of this work, hereby publish it under the following license:
Creative Commons CC-Zero This file is made available under the Creative Commons CC0 1.0 Universal Public Domain Dedication.
The person who associated a work with this deed has dedicated the work to the public domain by waiving all of their rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law. You can copy, modify, distribute and perform the work, even for commercial purposes, all without asking permission.

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1 February 2013

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