Pendulums
Mrs. Dickson
September 27, 2016
Question
Does mass affect
the swing of a
pendulum?
Research
A pendulum works by using gravity to transfer potential
energy to kinetic energy and back again. The amount of total
energy in the pendulum is determined by the size of the
mass at the end of the pendulum and the height the mass is
raised above its original position. As the pendulum swings,
the total energy is conserved, which means it remains
constant.
Gravity acts on the mass as soon as it is released. The mass
accelerates until it reaches the bottom of its swing and then
decelerates as it travels along its upswing. It momentarily
stops at the top of the swing and then reverses course.
Galileo discovered the pendulum effect. Galileo was sitting
in a church when he noticed that a chandelier was swinging.
He timed the chandelier's swing using his pulse as a
measuring device. Galileo realized that the chandelier took
the same amount of time to complete one full swing, no
matter how wide the swing was.
Independent
Variable
Mass
Dependent
Variable
Number of swings
Control Group
The pendulum with
the heavier weight
Experimental Group
The pendulum with the
lighter weight
Constants




Time
String length
Drop height
Type of string
Hypothesis
If the number of swings of a
pendulum is related to the
mass of the weight on the
pendulum, then the pendulum
with the greater mass will have
more swings then the
pendulum with the lighter
mass.
Material List







String
Paper clip
Pennies (2)
Tape
Pencil
Stopwatch
Ruler
Procedure
1. Build a pendulum by attaching a paper clip to one end of
the string.
2. Using the ruler, measure 38 cm and tape a loop at the
other end of the string. Make sure the loop is large
enough for a pencil to fit through.
3. Place a penny in the paper clip.
4. Tape a pencil to the edge of the table with about 1/2 of it
sticking off the edge.
5. Place the loop over the pencil. Make sure that when the
pendulum swings that it doesn't hit anything.
6. Using the stopwatch, count how many swings the
pendulum makes in 15 seconds.
7. Repeat step 6 two more times for a total of 3 trials.
8. Add a penny to the paperclip.
9. Repeat steps 6-7.
Data Table
1 Penny
Number
of Swings
2
Pennies
Number
of Swings
Trial 1
Trial 2
Trial 3
Average
12
12
12
12
Trial 1
Trial 2
Trial 3
Average
12
12
12
12
Graphs
Number of Swings
The Effect of Mass on a
Pendulum - 1 Penny
15
10
5
0
Trial 1
Trial 2
Trial 3
The Effect of Mass on a
Pendulum - 2 Pennies
Number of Swings
15
10
5
0
Trial 1
Trial 2
Trial 3
Number of Swings
The Effect of Mass on a
Pendulum - Average
15
10
5
0
1 Penny
2 Pennies
Pictures
Conclusion
My hypothesis was not
supported. Mass does not have
an effect on the swing of the
pendulum. The pendulum
swung 12 times no matter how
much mass was on it.