Physics

Experiments Solutions

For each measurement of the period, you should measure at least three times, take the
average and also calculate the standard deviation to use as a measure of the uncertainty. In
addition, to decrease the uncertainty of the measurement, you should measure the period of
10 oscillations and then divide by 10. This will make the reaction time, which contributes to
the uncertainty, a smaller percentage of the actual measurement. It is also useful for one
student to release the pendulum and another person to time the measurement. However, if the
student releases the pendulum and simultaneously tells the student timing to start the
stopwatch, this introduces another uncertainty. Instead, the student with the stopwatch should
let the pendulum swing through one oscillation before starting the stopwatch. This will
decrease the uncertainty in the measurement.
Investigation 1.1 Follow your procedure from Exploration 2 and the measurement procedure
described above. Test the three variables of mass, amplitude of the swing and length of the
string to see, if they influence the period. You should choose at least three different values
for each of the variables being tested. (So use three different masses, if you are testing mass,
etc.) The variables not being tested should be held constant. For example, if you test length
first, the mass and amplitude will be held constant for all measurements of length. Because it
is difficult to return to a previous length, the length should be measured first or last.
There is a table available on the next page to record your data. For every measurement,
repeat the measurement at least three times and record the mean and standard deviation of
those measurements.
3
Mass
Number of washers
1 washer = 28.2 g
1
Amplitude of swing = 10° , Length =42.5 cm
Measurement
Average and Uncertainty
in seconds
1.31
1.28
1.32
1.30
1.33
1.33
1.32
1.30
1.3.2
2
3
Amplitude of swing
Degrees
Length = 42.5 cm
Average and Uncertainty
10
Mass = 1 washer
Measurement
1.31
1.28
1.32
1.31
1.31
1.31
1.36
1.33
1.33
15
20
Length
10º, Mass = 1 washer
Average and Uncertainty
cm
95.7
Amplitude of swing =
Measurement
1.93
1.96
1.95
1.64
1.65
1.62
1.31
1.28
1.32
64.8
42.5