Testing Pendulum
Variables Lab
Names: ____________________________________
Date: ________________ Class Period: __________
In this lab you will construct your own pendulum apparatus and
then test different variables of the pendulum to see how they effect time of swing. You need to know that
the time it takes a pendulum to swing to the opposite side and back to it’s original starting position is called
the period of the pendulum. The variables you will be testing are length of string, mass of pendulum, and
angle of release. You will record your data in data tables and draw logical conclusions from what you
observed.
In this laboratory exercise your objectives will be to do the following:
Objectives:
 Measure length, time, mass, and angles correctly
 Correctly identify the independent variable, dependent variable, constants, and control in the
experiment
 Become familiar with the workings of a pendulum
 Become familiar with some common laboratory equipment
Materials Needed:
 Ring stand with clamp
 Stopwatch or timer
 Fishing line with loop in the end
 Mass set
 Protractor
 Meterstick
 Calculator
Warnings:
There are no safety requirements for this lab, but remember that lab equipment are not toys.
Hypothesis:
Before doing the experiment you need to make a hypothesis as to what you think is going to happen. Each
hypothesis you make needs to be in the form of an “If... then…” statement. Make a different hypothesis for
each of the following situations:
1. How do you think changing the length of the fishing line for the pendulum will effect the period of
the pendulum?
2. How do you think changing the amount of mass hanging on the end of the pendulum will effect
the period of the pendulum?
3. How do you think the angle of release of the pendulum will effect the period of the pendulum?
Hypothesis 1:
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Hypothesis 2:
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Hypothesis 3:
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Procedure: Part I: Varying the Mass
Follow this procedure exactly and you will get good results. Do not skip steps. If you have questions raise
your hand and I will help you.
1) One person from each group go to the counter at the back of the room and get the materials needed
for the lab.
2) Secure the fishing line to the clamp in such a manner that from the bottom of the clamp to the
bottom of the loop there is 25 cm of fishing line when it is pulled tight.
3) Attach a 50 g mass to the loop at the bottom of the fishing line.
4) With one person ready at the timer, and one person holding the mass ready to drop, drop the mass
and measure the time it takes the pendulum to complete 20 periods. (You will need to drop the
pendulum from the same spot each time, so pay attention to where you are dropping it from.)
1)
2)
3)
4)
5)
Record your data in Data Table 1 under Trial 1.
Repeat Step 4 and record your data in Data Table 1 under Trial 2.
Remove the 50 g mass and attach a 100 g mass to the loop.
Repeat steps 4 – 6.
Repeat the process for masses of 200 g, 250 g, and 300g recording your data as you go in the data
table.
6) Move to Procedure Part II
Procedure: Part II: Varying Length of Pendulum
1) Secure the fishing line to the clamp in such a manner that from the bottom of the clamp to the
bottom of the loop there is 10 cm of fishing line when it is pulled tight.
2) Attach a 50 g mass to the loop at the bottom of the fishing line.
3) With one person ready at the timer, and one person holding the mass ready to drop, drop the mass
and measure the time it takes the pendulum to complete 20 periods. (You will need to drop the
pendulum from the about the same angle each time, so pay attention to where you are dropping it
from.)
4) Record your data in Data Table 2 under Trial 1.
5) Repeat Step 3 and record your data in Data Table 2 under Trial 2.
6) Change the length of the fishing line to 20 cm and repeat steps 3-5.
7) Repeat the process for string lengths of 30cm, 40cm, and 50 cm recording your data in the table as
you go.
8) Move to Procedure Part III
Procedure: Part III: Varying Angle of Release
1) Secure the fishing line to the clamp in such a manner that from the bottom of the clamp to the
bottom of the loop there is 20 cm of fishing line when it is pulled tight.
2) Attach a 50 g mass to the loop at the bottom of the fishing line.
3) Measure the angle of release so that it is 75º from the vertical. (This means the angle between
straight up and down and where you are dropping it from is 75º.)
4) With one person ready at the timer, and one person holding the mass ready to drop, drop the mass
and measure the time it takes the pendulum to complete 20 periods.
5) Record your data in Data Table 3 under trial 1.
6) Repeat steps 3 & 4 and record your data in Data Table 3 under Trial 2.
7) Change the angle of release to 60º and repeat steps 4-6.
8) Repeat the process for angles of 45 º, 30 º, and 15 º recording your data in the data table as you go.
9) Have one of the class lab helpers bring your materials to the back of the room.
10) Begin work on calculating averages and answering lab questions.
Data Table 1
Varying Mass on the Pendulum
Amount of Mass
Time for 20 Periods (sec)
Trial 1
Trial 2
Average
50g
100 g
200 g
250 g
300 g
Data Table 2
Varying Length of the Pendulum
Length of String
Time for 20 Periods (sec)
Trial 1
Trial 2
Average
10 cm
20 cm
30 cm
40 cm
50 cm
Data Table 3
Varying Angle of Release of Pendulum
Angle of Release
Time for 20 Periods (sec)
Trial 1
Trial 2
Average
15 º
30 º
45 º
60 º
75 º
Lab Questions: (Make sure all your answers are incomplete sentences.)
1. How did your hypotheses compare to the actual results?
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2. Which of the variables tested had a significant affect on the period of the pendulum?
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3. Suppose you had a pendulum clock that indicates an earlier time than it really is. (This means it
has too few swings per minute.) What could you do to the clock to make it keep better time?
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4. Do you think that using the data from table 2 you could accurately predict what the time for 20
periods would be if the line length was 60 cm? Why do you think so?
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Identification of Variables
The independent variable in Part 1 : ________________________________________________
Part II: ________________________________________________
Part III:________________________________________________
The dependent variable in all parts was ______________________________________________
The constants in Part I: ___________________________________________________________
Part II: __________________________________________________________
Part III:__________________________________________________________
Bonus: Why did you not need a control in this experiment?