Physics 100 Lab
Pendulum Period & Frequency
Name
Date
Measure pendulum period and frequency with:
- varying amplitude (10o, 20o)
- varying length (100 cm, 50 cm, 25 cm), and
- varying mass (small and large).
Use the table provided for your data.
Period, T, is the time for the pendulum bob to swing back and forth, in other words, the time for the bob to
return to its starting location. Measure time taken for the bob to swing back and forth 20 times. Period
equals this time divided by 20.
Frequency, f, is the number of back and forth bob motions per second, in other words, the number of periods
per second. The unit for frequency is s-1 or Hz. Here are 2 ways to get frequency:
1. Measure period, T, and calculate the reciprocal to get frequency:
f = 1/T
2. Measure the number of back & forth motions (periods) in 20 seconds, say. Divide this number by 20 to
get frequency.
Determine frequency using both of the above methods – there is a column for each method in the data table.
Answer these questions
•
1. Increasing pendulum bob mass [increases/decreases/does not affect] pendulum
period.
•
2. Increasing pendulum length [increases/decreases/does not affect] pendulum
period.
•
3. If pendulum frequency increases, pendulum period decreases. [T/F]
•
4. Increasing pendulum amplitude [noticeably increases/ noticeably decreases/does
not affect] pendulum period.
•
5. Consider 2 identical pendula, E on the Earth, and M on the Moon. The period of E
is [less than/ greater than/equal to] the period of M.
•
6. Air resistance has absolutely no effect on pendulum period. [T/F]
Pendulum Vocab
Note: Choose d as follows to get Q:
L = length (m)
M = bob mass (kg)
Q = amplitude (degrees)
Q
L
M
d