1. Lab Improvements/Changes
10 cycles, then divide time by ten to get the period.
Period: the time it takes to complete one cycle
Person timing should be person releasing the weight

2. Data Collection Standards (see handout)
Measure and record all variables.
Conduct multiple trials (same thing several times). More trials are needed if there is a large variance between trials.
Record all trials, use average as the “final” value.

3. Collect as many data points as possible for each independent variable (8-10 is usually a good minimum number to aim for).
Collect data for each independent variable over as large a range as possible (a factor of at least 5 between minimum and maximum is best).

4. Your task is to collect data so that you can determine the mathematical relationship (equation) between the length of a pendulum and it’s period.
Make a plan with your group as to how you are going to update your procedure so that you get the best data possible.

5. Calculate the average for each set of data. Is there a difference?
Period (s)
Trial 1
Trial 2
Trial 3
Trial 4
Avg.
5.6
5.4
5.3
5.7
5.5
Period (s)
Trial 1
Trial 2
Trial 3
Trial 4
Avg.
2.1
9.9
3.2
6.8
5.5

6. Experimental Uncertainty
This is the measure of the variation between measurements/trials when we expect the same result.
𝑈𝑛𝑐𝑒𝑟𝑡𝑎𝑖𝑛𝑡𝑦= 𝐿𝑎𝑟𝑔𝑒𝑠𝑡 𝑣𝑎𝑙𝑢𝑒−𝑠𝑚𝑎𝑙𝑙𝑒𝑠𝑡 𝑣𝑎𝑙𝑢𝑒 2

7. Calculate the uncertainty for each set of data. Is there a difference?
Period (s)
Trial 1
Trial 2
Trial 3
Trial 4
Avg.
5.6
5.4
5.3
5.7
5.5±0.2
Period (s)
Trial 1
Trial 2
Trial 3
Trial 4
Avg.
2.1
9.9
3.2
6.8
5.5±3.9

8. Example 1: Jose measured the width of a room 3 times
Example 1: Jose measured the width of a room 3 times. Calculate the experimental uncertainty in his measurements. d1 = 4.25 m, d2 = 4.31 m, d3 = 4.26 m 4.31𝑚−4.25𝑚 2 =.03 m davg = 4.27±.03 m
(experimental uncertainty)

9. Example 2: We have four time measurements for the period of a pendulum that has a length of 550 mm: T1 = 1.35 s, T2 = 1.42 s, T3 = 1.41 s, T4 = 1.45 s. Calculate the average and experimental uncertainty.

10. Length: 550 mm
T1 = 1.35 s, T2 = 1.42 s, T3 = 1.41 s, T4 = 1.45 s.
1.45𝑠−1.35𝑠 2 =.05 s
Tavg = 1.41±.05 s

11. Experimental uncertainty needs to be calculated for each set of trials.
If you have just one experimental uncertainty for the entire lab, you are doing it wrong.

12. Homework Start lab report (bring printed out) Intro Procedure Data
Graphs
Includes initial plot and linearize plot