Name: ______
Lab Partner______
Simple Pendulum
Materials: thread, meter stick, stopwatch, ring stand, protractor, various masses, Vernier LabPro with Photogate
Procedure: PART 1
· you are to construct a simple pendulum
· your simple pendulum will consist of a mass (bob) suspended from a ring stand by a thread which can swing freely
· amplitude (angular displacement θ) of the pendulum is the angle from which the bob is released
· length (L) is the length of the thread to the center of gravity of the mass
· you will calculate the period (T) (the time it takes for the pendulum bob to swing from one side to the other and back again) while varying the mass, length, and angular displacement of the pendulum
· the bob should go through 10 cycles each run
· make sure to verify mass on the scale and accurately measure length
A. Does mass affect the period of a pendulum?
1. Use a length of string between 0.50 m and 1.50 m. Tie a 25g mass to the string. Pull the pendulum bob back 15° and record the time it takes for the pendulum to make 10 complete cycles. Divide this time by 10 to get the period of the pendulum.
2. Record this information in DATA TABLE 1A.
3. Repeat the same procedure for the different masses listed. Change only the mass. Keep all other variables CONSTANT!
4. Record all information in DATA TABLE 1A.
B. Does length affect the period of a pendulum?
1. Find the period of the pendulum as above, using a constant mass and amplitude in each run, and varying only the pendulum’s length as listed in the data table.
2. Record all information in DATA TABLE 1B.
C. Does amplitude affect the period of a pendulum?
1. Find the period of the pendulum as above, using a constant mass and length in each run, and varying only the pendulum’s amplitude as listed in the data table.
2. Record all information in DATA TABLE 1C.
Now use the pendulum equation
to calculate the acceleration of gravity (g)
for each trial.
DATA TABLE 1A – Variable Mass
Mass (m)g / Length(L)
m / Amplitude
θ / Time s
10 cycles / Period (T)
s / Gravity (g)
m/s2
25
50
75
100
150
DATA TABLE 1B – Variable Length
Mass (m)g / Length(L)
m / Amplitude
θ / Time s
10 cycles / Period (T)
s / Gravity (g)
m/s2
0.20 m
0.40 m
0.60 m
0.80 m
1.00 m
0.20 m
1.40 m
1.60 m
1.80 m
DATA TABLE 1C – Variable Amplitude
Mass (m)g / Length(L)
m / Amplitude
θ / Time s
10 cycles / Period (T)
s / Gravity (g)
m/s2
10
15
25
35
45
D. Results:
1. Make a graph for each of the data tables: “Period vs Mass” 1A “Period vs Length” 1B “Period vs Amplitude” 1C
2. On each graph write a statement about the relationship (if any) between the period and the variable.
3. Write a short paragraph about the acceleration of gravity (g) and its dependence or lack of dependence on mass, length, and amplitude for a simple pendulum.
PART 2
A. Use LabPro to test your results.
1. Repeat A, B, and C above using the Vernier LabPro and Photogate.
2. The LabPro will calculate much of the data for you if you put in the correct constants.
3. Do all the calculations as before including the acceleration of gravity.
4. Make graphs for the three data tables including a sentence about the relationship of period to the variables.
5. Write a summary paragraph discussing what you learned from this activity and how your results without using the LabPro compared with results using LabPro. Include which results you think are more accurate and why. Also include where errors may have occurred and why.
DATA TABLE 2A – Variable Mass
Mass (m)g / Length(L)
m / Amplitude
θ / Time s
10 cycles / Period (T)
s / Gravity (g)
m/s2
25
50
75
100
150
DATA TABLE 2B – Variable Length
Mass (m)g / Length(L)
m / Amplitude
θ / Time s
10 cycles / Period (T)
s / Gravity (g)
m/s2
0.20 m
0.40 m
0.60 m
0.80 m
1.00 m
0.20 m
1.40 m
1.60 m
1.80 m
DATA TABLE 2C – Variable Amplitude
Mass (m)g / Length(L)
m / Amplitude
θ / Time s
10 cycles / Period (T)
s / Gravity (g)
m/s2
10
15
25
35
45
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