Go Back   Physics Help Forum > College/University Physics Help > General Physics

General Physics General Physics Help Forum

Reply
 
LinkBack Thread Tools Display Modes
Old Feb 25th 2017, 03:10 PM   #1
cxz
Junior Member
 
Join Date: Feb 2017
Posts: 5
Determine the natural frequency 2

The question is:

Determine the natural frequency of the rotor shown below given the following data:
Moment of inertia of rotor Jr=0.6 kgm^2
Diameter of shaft d=38.0mm
Length of shaft L=189.0 mm
Material of shaft Steel Modulus of Rigidity 82 GPa

My solution is:

I=(π*d^4)/64=(π*0.038^4)/64=102e-9
ω=((J*G)/(I*L))^0.5=((0.6*82e9)/(102e-9*0.189))^0.5=1.598e9
F=1.598e9/2π=0.254e9

The correct answer should be 61.2 what am I doing wrong?
Attached Thumbnails
Determine the natural frequency 2-capture7.jpg  
cxz is offline   Reply With Quote
Old Mar 8th 2017, 10:57 AM   #2
Senior Member
 
Join Date: Jul 2009
Location: Kathu
Posts: 114
Determine the natural frequency 2

J=PI()/32*(38*10^-3)^4= 2.04708E-07 m^4
G = 82000000000 GPa
L = 0.189 m
I = 0.6 kg * m^2

ω=((J*G)/(I*L))^0.5 = 384.740176 Rads / sec
F = W / (2*pi) = 61.23 Hz
YellowPeril is offline   Reply With Quote
Reply

  Physics Help Forum > College/University Physics Help > General Physics

Tags
determine, frequency, natural



Thread Tools
Display Modes


Similar Physics Forum Discussions
Thread Thread Starter Forum Replies Last Post
Determine the natural frequency cxz General Physics 1 Feb 24th 2017 11:36 AM
Resonance,Resonance frequency,natural frequency? hyungjko Waves and Sound 1 Feb 7th 2013 12:33 PM
Water natural convection Rockandroll Thermodynamics and Fluid Mechanics 1 Dec 3rd 2012 12:44 PM
Strain and natural length werehk Equilibrium and Elasticity 3 Jul 27th 2009 09:10 PM
Determine H? reverseswing Advanced Electricity and Magnetism 1 Jun 19th 2009 02:52 AM


Facebook Twitter Google+ RSS Feed