ex1 - EXPERIMENT 1 Introduction to Computer Tools and...

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EXPERIMENT 1 Introduction to Computer Tools and Uncertainties Objectives To become familiar with the computer programs and utilities that will be used throughout the semester. You will learn to use Microsoft Excel and Kaleidagraph to perform some simple tasks. To become familiar with experimental uncertainties. A few starters: Always bring a floppy disk or flash memory drive with you to class and save your work often. The Excel spreadsheet is made up of rectangles called “cells”. Kaleidagraph is a graphing program that you will use to analyze the data we compute in the Excel spreadsheet. Once you have the data you can make a graph that will quickly and easily show what trends or relations the data exhibits. Kaleidagraph is versatile and allows you complete control over how the data will be presented. It is up to you to decide (or to be instructed) as to what kind of graph will be best. Theory Microsoft Excel is a spreadsheet program that allows you to manipulate text as well as data. Most importantly for the labs you will be doing, Excel can perform calculations quickly that would otherwise be very time consuming. Learning a few basic commands and skills in Excel now will save you a considerable amount of calculation time the rest of the semester. Uncertainties The scientist endeavors to make measurements subject to as little uncertainty (often colloquially called “error”) as possible. Here error does not mean a mistake, but rather a physical inability to make perfect measurements. All measurements are to some extent imperfect, and therefore the results obtained are always subject to some uncertainty. The scientist must indicate the magnitude of these uncertainties. We express the uncertainty of a quantity x by writing x ± δ x, where δ x is the uncertainty of x. Uncertainties are always: positive numbers have the same units as the quantity in the equation
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Random Errors: When you make a series of measurements of the same quantity using the same measuring instruments, you often find that you do not obtain exactly the same answer each time. Your measurements are said to be affected by random errors . Random errors arise from small, uncontrollable differences in the way each measurement was made. Random errors determine the uncertainty in the value of a directly measured or calculated quantity. Systematic Errors: If the measured value differs systematically from the correct value, then the measuring equipment is said to contain systematic errors . Such errors can result from either improper calibration of the equipment or from a failure to account properly for some unexpected perturbation such as friction. These errors are generally harder to estimate than random errors. Some general rules about uncertainties:
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This note was uploaded on 07/25/2008 for the course PHY 251 taught by Professor J.t. during the Summer '08 term at Michigan State University.

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ex1 - EXPERIMENT 1 Introduction to Computer Tools and...

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