Processing Math: Done
To print higher-resolution math symbols, click the
Hi-Res Fonts for Printing button on the jsMath control panel.
No jsMath TeX fonts found -- using image fonts instead.
These may be slow and might not print well.
Use the jsMath control panel to get additional information.
jsMath Control PanelHide this Message

jsMath

13. Moments

From Mechanics

Jump to: navigation, search
       Theory          Exercises          Video      

Key Points

The moment of a force about the point O is the product of the force and the perpendicular distance to the line of action of the force from O.

Image:T13.1.GIF Moment =Fd

Image:T13.2.GIF Moment =Fdsin

Clockwise moments are negative.

Anti-clockwise moments are positive.

The resultant moment about O is the sum of the moments about O.


Example 13.1

Image:ex13.1whole.GIF

Example 13.2

Image:ex13.2.GIF


Example 13.3

For the rectangular lamina shown below, find the total moment of the forces acting, about the corner marked O.

Image:ex13.3.GIF

Solution

Force Moment (Nm)
5N at O 50=0
8 N −81.2=−9.6
7 N 70=0
6 N −60.5=−3
5 N 51.2=6
4 N 40.5=2
Total Moment 0−9.6+0−3+6+2=−4.6 Nm
Retrieved from "http://wiki.math.se/wikis/2009/bridgecoursemechanics/index.php/13._Moments"