Go Back   Physics Help Forum > High School and Pre-University Physics Help > Kinematics and Dynamics

Kinematics and Dynamics Kinematics and Dynamics Physics Help Forum

Reply
 
LinkBack Thread Tools Display Modes
Old Oct 30th 2015, 02:26 AM   #1
Senior Member
 
Join Date: Jun 2014
Posts: 306
moment for 3D model

in this case( involve 3D model) , it give the moment about the x , y , x' and y' axis .... can we find the moment about a specific point? (i.e. can we find the moment about the O ( centroid) ) ?
Attached Thumbnails
moment for 3D model-02.jpg   moment for 3D model-01.jpg  
ling233 is offline   Reply With Quote
Old Oct 30th 2015, 12:59 PM   #2
Physics Team
 
ChipB's Avatar
 
Join Date: Jun 2010
Location: Morristown, NJ USA
Posts: 2,333
Originally Posted by ling233 View Post
. can we find the moment about the O ( centroid) ?
Sure. But it won't do you much good with respect to solving this problem though. Choosing to calculate moments through the x'- and y'-axes simplifies the problem nicely.
ChipB is offline   Reply With Quote
Old Oct 30th 2015, 07:59 PM   #3
Senior Member
 
Join Date: Jun 2014
Posts: 306
Originally Posted by ChipB View Post
Sure. But it won't do you much good with respect to solving this problem though. Choosing to calculate moments through the x'- and y'-axes simplifies the problem nicely.
do u mean if i choose to find the moment about O , then i would have to find the moment about x , y , z axis about O ? in 3D question , if i choose to find the moment about a single point , then i would have to get the moment about the x, y, z of forces for the specific point ?
ling233 is offline   Reply With Quote
Old Oct 31st 2015, 07:27 AM   #4
Physics Team
 
ChipB's Avatar
 
Join Date: Jun 2010
Location: Morristown, NJ USA
Posts: 2,333
You may choose to calculate moments about any point that you want. You have a total of 6 equations to play with at any point (three for forces in x-, y-, and z-dimensions and three for moments about x-, y- and z-axes). So as long as there are no more than 6 unknowns you should be able to find a solution (if one exists) no matter which point you choose to use as O, and no matter which particular directions you choose for x-, y- and z-axes (as long as they are independent, or better yet orthogonal to each other). However, by using some judgment about selecting which point to use and which way the axes are oriented you can often reduce these 6 equations to a more manageable number, thus making the problem much easier to solve. For example in this problem by selecting axes x', y' and z' the 6 equations simplify to become just two.
ChipB is offline   Reply With Quote
Reply

  Physics Help Forum > High School and Pre-University Physics Help > Kinematics and Dynamics

Tags
model, moment



Thread Tools
Display Modes


Similar Physics Forum Discussions
Thread Thread Starter Forum Replies Last Post
Bohr model and energy mss90 Energy and Work 10 Dec 18th 2014 01:54 PM
Spin Foam Model Jerromyjon Quantum Physics 5 Nov 22nd 2014 07:07 AM
model with mirror suvadip Light and Optics 1 Sep 10th 2013 09:38 AM
Monopole moment, Dipole Moment and a Quadruple Moment Nimmy Advanced Electricity and Magnetism 0 Oct 27th 2011 10:00 AM
About a science model soumyadip_2k Thermodynamics and Fluid Mechanics 1 Oct 5th 2008 07:44 AM


Facebook Twitter Google+ RSS Feed