Tuesday, Feb 5, 2008

Lecture on Dealing with Uncertainty in Physics
Lectured on uncertainties:
1. If you have multiple measurements:
Find the average by: (M1 + M2 + ... + Mn)/n
Find the uncertainty by: (abs(M1-avg) + abs(M2-avg) + ... + abs(Mn-avg))/n

2. If you have one measurement of each quantity:
2a. Max Min method
Example of area of a rectangle
Max area = (L + uncL)*(W + uncW)
Min area = (L - uncL)*(W - uncW)
Avg area = (Max area + Min area)/ 2
Unc Area = (Max area - Min area)/ 2

2b. Method of Relative Uncertainty
This method cannot be used if the terms are added or subtracted but otherwise is powerful and easy to use
Used example of area of a rectangle
Area = L * W
Unc Area = A * (uncL/L + uncW/W)

If you have a complicated expression like: Z = (A^1/2) * (B^3)/(C^5)
you can use this method taking the absolute values of the exponents as coefficients in the relative uncertainty equation: uncZ = Z*((1/2)*uncA/A + 3*uncB/B + 5*uncC/C)

Handed out practice sheet on uncertainties with summary of class notes - will post answers in answer folder.

Students did Spring Constant Lab - uncertainties not needed
Write-up: Name, Partners, Date, Lab Title
Data Table
Picture with calculations
Results: Discuss summary questions
Answer questions making sure to explain in answer what it is you are answering

Spring Constant Lab due on Thursday

Talked about Pumpkin Labs
Part 1: Emphasize Data Collection and Data Manipulation
Part 2: Emphasis on IB Planning (b) (Method), and Conclusions