[Note: this is not one of the assigned possibilities! It is here only as an example.]
Observed Phenomena: A weight on a string swings back and forth. Questions: are the swings of equal duration? Does the period of the swing depend on the suspended mass or on the length of the string or both?
Hypothesis 1: The period (time to make one back and forth swing) of the pendulum are of duration if no change is made to the mass or length of the string.
Hypothesis 2: The period increases if the length of the string increases, and shortens if the length of the string shortens. Another way to say this: the period is directly dependent on the length of the string.
Equipment and Materials:
- Hook bored into ceiling beam 2.5m above floor)
- Hook and bag to hold weights.
- String of different related lengths: .1m, .5m, 1.0m, 1.5m, 2.0m
- Weights of different masses: 1/4 lb, 1/2 lb, 1 lb, 2 lbs (made by filling bag with beans, weighed on kitchen scale).
- Timer or stop watch (used iPhone timer)
- Protractor to measure angle of displacement
Procedure:
- Tie 0.1m string to ceiling hook, fill bag with 1/4 lb beans.
- Displace weight 30deg from vertical and release.
- Time 5 swings and record elapsed time.
- Repeat 3 times (4 total attempts); calculate and record average period for length/mass.
- Repeat steps 1-4 with same string using 1/2 lb, 1lb and 2 lb masses.
- Repeat steps 1-5 with each string (0.5m, 1.0m, 1.5m, 2.0m)
Analysis:
- Determine range of values for each length/mass combination to determine whether the period is constant for a given length/mass within experimental error.
- Using average period for each length/mass combination, plot period as function of mass.
- Using average period for each length/mass combination, plot period as function of string length.
- From plots, determine whether mass or length affect the period of the swing, and if so, how.
| String length |
0.10 |
0.10 |
0.10 |
0.10 |
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| Weight in lbs |
0.25 |
0.50 |
1.00 |
2.00 |
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| Mass in kg |
0.11 |
0.23 |
0.45 |
0.91 |
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| Trial 1 |
0.63 |
0.63 |
0.63 |
0.63 |
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| Trial 2 |
0.64 |
0.61 |
0.62 |
0.65 |
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| Trial 3 |
0.63 |
0.63 |
0.62 |
0.65 |
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| Trial 4 |
0.63 |
0.65 |
0.63 |
0.64 |
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| Average |
0.63 |
0.63 |
0.63 |
0.64 |
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| String length |
0.50 |
0.50 |
0.50 |
0.50 |
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| Weight in lbs |
0.25 |
0.50 |
1.00 |
2.00 |
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| Mass in kg |
0.11 |
0.23 |
0.45 |
0.91 |
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| Trial 1 |
1.42 |
1.42 |
1.42 |
1.42 |
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| Trial 2 |
1.42 |
1.43 |
1.43 |
1.44 |
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| Trial 3 |
1.43 |
1.65 |
1.42 |
1.43 |
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| Trial 4 |
1.43 |
1.43 |
1.42 |
1.44 |
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| Average |
1.42 |
1.48 |
1.42 |
1.43 |
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| String length |
1.00 |
1.00 |
1.00 |
1.00 |
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| Weight in lbs |
0.25 |
0.50 |
1.00 |
2.00 |
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| Mass in kg |
0.11 |
0.23 |
0.45 |
0.91 |
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| Trial 1 |
2.01 |
2.01 |
2.01 |
2.01 |
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| Trial 2 |
2.00 |
2.01 |
2.03 |
1.98 |
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| Trial 3 |
2.01 |
2.01 |
2.01 |
1.99 |
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| Trial 4 |
2.03 |
2.01 |
1.99 |
2.01 |
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| Average |
2.01 |
2.01 |
2.01 |
2.00 |
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| String length |
2.00 |
2.00 |
2.00 |
2.00 |
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| Weight in lbs |
0.25 |
0.50 |
1.00 |
2.00 |
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| Mass in kg |
0.11 |
0.23 |
0.45 |
0.91 |
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| Trial 1 |
2.84 |
2.84 |
2.84 |
2.84 |
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| Trial 2 |
2.84 |
2.84 |
2.84 |
2.88 |
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| Trial 3 |
2.83 |
2.88 |
2.85 |
2.85 |
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| Trial 4 |
2.85 |
2.78 |
2.80 |
2.79 |
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| Average |
2.84 |
2.83 |
2.83 |
2.84 |
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| SUMMARY |
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0.10 |
0.50 |
1.00 |
2.00 |
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| 0.25 |
0.63 |
1.42 |
2.01 |
2.84 |
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| 0.50 |
0.63 |
1.48 |
2.01 |
2.83 |
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| 1.00 |
0.63 |
1.42 |
2.01 |
2.83 |
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| 2.00 |
0.64 |
1.43 |
2.00 |
2.84 |
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