1. Turn in lab reports and WS 1 to the front basket. Remember to attach your draft.

2. Experimental Uncertainty

3. How to report a measurement Average value ± uncertainty 34.3 ±.2 s

4. (experimental uncertainty)

5. Example 2: We have four time measurements for the period of a pendulum that has a length of 550 mm: T 1 = 1.35 s, T 2 = 1.42 s, T 3 = 1.41 s, T 4 = 1.45 s. What is the average value for the period? (include experimental uncertainty when reporting the average)

6. Length: 550 mm T 1 = 1.35 s, T 2 = 1.42 s, T 3 = 1.41 s, T 4 = 1.45 s.

7. Calculate the percent error for this measurement.

8. Range of experimental uncertainty Accepted value Average measured value

9. Apparatus Precision This is a measure of “fineness” of a measurement– the smallest increment that your apparatus will measure. It’s not how correct the measurement is, it’s how well you know it. – Example: 15.345 cm is more precise than 15.3 cm. The first measurement has a precision of 0.001 cm and the second has a precision of 0.1 cm. – Note: Just because a tool is precise doesn’t mean it’s accurate!

10. Apparatus precision and experimental uncertainty activity.

11. How to Analyze a Linear Graph General trend Slope (+ or - ) Slope (units) Slope (physical meaning) y-intercept (+ or - ) y-intercept (units) y-intercept (physical meaning) General physics equation