1. INTRODUCTION TO ENGINEERING TECHNOLOGY SEVENTH EDITION ROBERT J. POND & JEFFERY L. RANKINEN Chapter 7 The Technical Laboratory

2. INTRODUCTION This chapter is intended to make you aware of how to work safely and effectively in the laboratory and report your findings clearly and efficiently. This chapter is intended to make you aware of how to work safely and effectively in the laboratory and report your findings clearly and efficiently.

3. LABORATORY TECHNICIAN Be patient and methodical Be patient and methodical Pay attention to detail Pay attention to detail Plan and prepare Plan and prepare Be accurate Be accurate Communicate clearly and effectively Communicate clearly and effectively

4. SCIENTIFIC METHOD – PROBLEM SOLVING State the problem State the problem Form the hypothesis Form the hypothesis Experiment and observe Experiment and observe Interpret the data Interpret the data Arrive at the conclusion Arrive at the conclusion

5. PERFORMING THE EXPERIMENT Equipment specified Equipment specified Data sheets Data sheets Group work Group work Conclusions drawn Conclusions drawn

6. REDUCING ERRORS IN THE LAB There is always variability during an experiment. There is always variability during an experiment. All measurements are subject to variability. All measurements are subject to variability. You must learn to recognize the major causes of variability and eliminate as many as possible. You must learn to recognize the major causes of variability and eliminate as many as possible. You then must record those that are impossible to eliminate. You then must record those that are impossible to eliminate. Include any causes of error in your laboratory report. Include any causes of error in your laboratory report.

7. TYPES OF ERRORS There are 3 general categories of errors, gross, systematic, and random. There are 3 general categories of errors, gross, systematic, and random. Gross errors completely invalidate the data. Gross errors completely invalidate the data. Must be eliminated Must be eliminated Not discussed in the report Not discussed in the report Include misuse of equipment, not following the procedure, recording data incorrectly Include misuse of equipment, not following the procedure, recording data incorrectly

8. TYPES OF ERRORS Systematic errors exhibit an orderly character, that is, across the board on all of the experiment. Systematic errors exhibit an orderly character, that is, across the board on all of the experiment. Caused by the environment, the measuring instrument, or the experimenter. Caused by the environment, the measuring instrument, or the experimenter. Try to eliminate Try to eliminate Often not reported in the lab report. Often not reported in the lab report. Include Include Equipment out of calibration Equipment out of calibration Failure of mechanical devices due to temperature, continued use, etc. Failure of mechanical devices due to temperature, continued use, etc. Gauges affected by pressure or temperature Gauges affected by pressure or temperature Hysteresis Hysteresis Observation errors Observation errors Adjusting data or continued retesting to get a desired result Adjusting data or continued retesting to get a desired result

9. TYPES OF ERRORS Random errors are due to chance causes Random errors are due to chance causes They affect measurements at different times and in varying directions. They affect measurements at different times and in varying directions. May vary in magnitude May vary in magnitude Environmental errors may also be random Environmental errors may also be random May include air drafts/currents, unknown temperature fluctuations, relative humidity May include air drafts/currents, unknown temperature fluctuations, relative humidity Can never be eliminated Can never be eliminated Try to reduce impact on experiment Try to reduce impact on experiment Average data Average data If the errors become know (such as humidity increasing), include the information in the report. If the errors become know (such as humidity increasing), include the information in the report.

10. DATA COLLECTION AND CALCULATING RESULTS Scale Resolution – no better than one-half of the smallest division Scale Resolution – no better than one-half of the smallest division

11. PRESENTING DATA Data can be presented in various ways. Data can be presented in various ways. Tables Tables Graphs Graphs Use an X-Y coordinate grid. Use an X-Y coordinate grid. The variable you control is the independent variable The variable you control is the independent variable Always on the X axis Always on the X axis The other variable is the dependent variable The other variable is the dependent variable Dependent on any change in the independent variable Dependent on any change in the independent variable Always on the Y axis Always on the Y axis Interpolation is using the line or curve made from connecting the data points to estimate another data point not specifically measured. Interpolation is using the line or curve made from connecting the data points to estimate another data point not specifically measured. Extrapolation is estimating a data point beyond the line or curve made from the measured data. Extrapolation is estimating a data point beyond the line or curve made from the measured data.

12. REPORTING Objective section Objective section Equipment section Equipment section Theory section Theory section Procedure section Procedure section Data section Data section Calculation section Calculation section Results section Results section Conclusion section Conclusion section Preparing and submitting the report Preparing and submitting the report The report checklist The report checklist Oral reporting Oral reporting Oral report checklist Oral report checklist Outlining the written report