Introduction to Engineering Mechanics

Introduction to Engineering Mechanics Dr. Wayne Whiteman Director of the Office of Student Services and Senior Academic Professional School of Mechanical Engineering

This course is an introduction to learning and applying the principles required to solve engineering mechanics problems.

School of Mechanical Engineering

Module 11 Learning Outcome 

Calculate the moment of a force about a line/axis

2

Moment of a Force about a Line/Axis M line/ axis 

 r  F   uˆ 

uˆ

Used with permission from “Engineering Mechanics: Statics,” McGill/King, 4th Ed, 2003

3

EXAMPLE: The chain in the figure below carries 20 lb of tension as it holds open the trap door. Find the moment of the chain force exerted at A, about the x-axis.

Moment of a Force about a Line/Axis

M line/ axis  r  F  uˆ



uˆ

Used with permission from “Engineering Mechanics: Statics,” McGill/King, 4th Ed, 2003

4

EXAMPLE: The chain in the figure below carries 20 lb of tension as it holds open the trap door. Find the moment of the chain force exerted at A, about the x-axis.

Using what you learned in Module 4, express the 3D force in vector form exerted by the chain at point A.

Moment of a Force about a Line/Axis

M line/ axis  r  F  uˆ



uˆ

Used with permission from “Engineering Mechanics: Statics,” McGill/King, 4th Ed, 2003

5