Pendulums
and the
Passing of Time
Background
Information: Everyone who has witnessed the back and
forth swinging motion of a grandfather clock is familiar with a pendulum. Time was probably first measured by marking
the shadow of the sun made by a stationary object (as in a sundial). This is an effective way of determining the
hour of the day for example. Pendulums
are one of the simplest devices used to measure time. In this experiment you will determine the effects of mass and
length on the period of a pendulum.
Cycle – A complete motion that begins and ends
in the same position.
Amplitude (A) – The degree to which an object is
moved from its initial or resting position
Period (T)
– The time it takes to complete one cycle.
meter
stick String
( 1 m) Pendulum apparatus
Procedure: There are
three parts to this experiment, read all instructions before proceeding.
Note in this part of
the experiment the length will be held constant at 0.60 m,
and the amplitude will be held constant at 50
degrees.
1.
Assemble a table top stand and attach a pendulum
clamp. Thread one end of the string
through clamp and secure with the thumb screw.
2. Tie a loop in the end of
the string, and hang a 20 gram mass on the end.
3.
Loosen the thumbscrew and adjust the string until the
pendulum is 0.60 m in length. Measure
from the point of attachment to the center of the pendulum mass.
4.
Using a timer, measure the time it takes to
complete ten full swings (cycles) of the pendulum. Record this number in your data table.
5. Divide the total time by 10
to find the time of one cycle. Watch
for significant digits. This number is
the period. Record this number in the
data table.
6. Repeat
the above procedure using masses of 50, 100, 150, and 200 g.
Note:In this part of
the experiment the length will be held constant at 0.60 m,
and the mass will be
held constant at 50 g.
1. Attach the 50 g mass and
position the string so the pendulum has a length of
0.60 m. Measure from the point of attachment to the
center of the pendulum.
2.
Using a timer, measure the time it takes to complete
ten full swings (cycles) of the pendulum when released from an amplitude of 30
degrees. Record this number in your
data table.
3. Divide the total time by 10
to find the time of one cycle. Watch
for significant digits. This number is
the period. Record this number in the
data table.
4. Repeat
Steps 1-3 for amplitudes of 40, 50, 60,
and 70 degrees.
Note: In this part of the experiment the mass will
be held constant at 50g,
and the amplitude
will be held constant at 50 degrees.
1. Attach the 50 g mass and
position the string so the pendulum has a length of
0.10 m. Measure from the point of attachment to the
center of the pendulum.
3.
Using a timer, measure the time it takes to
complete ten full swings (cycles) of the pendulum. Record this number in your data table.
3. Divide the total time by 10
to find the time of one cycle. Watch
for significant digits. This number is
the period. Record this number in the
data table.
4. Repeat
Step 1 for lengths 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, and 0.80 m.
Part 1. Construct
a graph of Period Vs. Mass of a pendulum.
Make sure to follow proper
graphing procedures.
Part 2. Construct
a graph of Period Vs. Amplitude of a pendulum.
Make sure to follow proper
graphing procedures.
Part 3. Construct
a graph of Period Vs. Length of a pendulum.
Make sure to follow proper
graphing procedures.
Note: Always
draw graphs in pencil so you can erase when you make errors, and always use
square lined graph paper!
1. Put the independent
(manipulated) variable on the x-axis (horizontal).
2. Put the dependent
(responding) variable on the y-axis (vertical).
3. Label
both axes and include units.
4.
Label the top of the graph with a title.
5.
Clearly place all data points on the graph.
6.
If appropriate, draw a best fit line or curve to
fit the data.