Principles of Problem Solving
PPS-14s: Translation/Define the System (Statics)
from MPS 8,
What is It?
Translation is part of the Explore step in the Six Step Method of Engage, Define, Explore, Plan, Do It, and Look Back.
By now you have Defined the Stated Problem and have listed the Goals/Unknowns, Given/Knowns, Constraints, Assumptions, and have perhaps drawn a picture or two describing the situation.
Next we need to define the system that we intend to analyze, and translate the words of the problem statement into engineering symbols and equations. Definition of the system often goes hand in hand with the principles used to solve the problem, but identification of principles is not the focus of this unit.
System Boundary, Input, Output, Free Body Diagram
Why Do It
In many Mechanical Engineering courses, the critical final step in problem definition is drawing the System, identifying the state of the System, and identifying all inputs and outputs to the System. This System Diagram is the precursor to applying the principles of Conservation of Mass and Energy and is important for the task of accounting for the flows through the system.
In the Solid Mechanics area (Statics, Dynamics, Mechanics of Materials), these System Diagrams are called Free Body Diagrams.
How to Do It
In this unit we are going to concentrate on translation as applied to Engineering Statics. Using problems from Statics, we will translate words to equations and draw and label Free Body Diagrams.
Words into symbols
Forces and Moments
Use my old notes for FBD and book pictures
Given a Statics problem statement, you should be able to Define the System by:
Exercise 1 (5 min.): (instructor hands out problem statement)
As an individual
As a group of 2-4 people
PPS-13 Define the Stated Problem
Assignment 1 Individual
For the problem statement assigned,
a. show appropriate forces and moments at locations where supports were cut
b. show all external or applied forces and moments on the system
c. using correct notation, label all forces and moments
1. Circumscribe Situation Drawing
Excellent (10) - continuous line that clearly shows where supports are cut
Mediocre (5) - some of line is not shown or not clear
Weak (0) - line is not continuous, cuts are unclear
2. Appropriate Forces Moments
Excellent (10) – all applied forces and moments are shown, appropriate forces and moments are shown where supports were removed
Mediocre (5) - some forces and moments are missing or incorrect
Weak (0) – most forces and moments are missing or incorrect
Excellent (10) – Forces and moments are labeled correctly (correct vector notation, units, directions, subscripts)
Mediocre (5) - some labels are incorrect or missing
Weak (0) – most labels are incorrect or missing