Phuc, Vinh, and Quang

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Pendulum Lab
Period 3rd 5-17-02

• By
• Phuc, Vinh, and Quang

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Purpose

• The purpose of this lab is to know what a
  independent, dependent, and constant variables
  are, and to manipulate them to determine what
  affects the period of a pendulum.

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Developing the Lab
Upon developing a lab we first come up with as
much things that will affect The lab as possible
and here are the things that the class came up
with
These are some of the brainstorm list we could
come Up with but of course we can come up with
more but They probably wont much to do with the
lab or we Know that it wouldnt. That would be
like coming up with Temperature of the room,
or material of string. These Variables probably
wouldnt affect such a lab.
Gravity Length of string Mass of weight Angle of
release Air resistance Period Distance Time
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Developing the Lab
We then picked out the main variable we will deal
with.
Independent
Dependent
Period Time
Length of string Angle of release
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Conducting the Lab
Procedure

• Gather all material require for the lab. Material
  contain a long string, a stop watch, a photo
  gate, a lab pro, and a computer to record the
  time.
• Assemble the photo gate like in the picture on
  the right. Having a long string and a mass
  connected to the end of the string.
• The computer are connect to the lab pro, which is
  connected to the photo gate to record the time.
• Picking 10 data point from the string and then
  test to see if the length of the string has any
  effect on the time.

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Conducting the Lab
Or the angle of the String
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2
Either measure the Length of the string
Either measure the Length of the string Or the
angle of the String then start the Experiment.
Get the Time then calculate Velocity.
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3
then start the Experiment
Get the Time then calculate Velocity.
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Analyzing the Lab
Data
After getting at least ten data point we start a
graph

• The data that we connect from the lab show us
  that the length of the string changes the time
  recorded. We also tested with the mass of the
  weight and string to see if it has any effect on
  the time. The result was that it does not has any
  effect on the lab.

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Analyzing the Lab
Evaluation of Data

• The math model, the slope means the time required
  to for the metal to make a complete swing.
  Length was raised to the square root was to
  linear the graph. The graph is the square root
  of length, which made a lot of sense because we
  all know that the more time there is for
  something to fall freely in 9.8m/s2, the greater
  its velocity. Therefore that tells us that it
  would take less time to cover a certain distance
  when the velocity is greater. The y-intercepts
  would mean how many seconds it would take for the
  metal piece to complete a period when the length
  of the string is zero. Again we can always
  calculate our percent error by dividing the y-int
  by the y-max. Which gave us what we had above.
  With only .09 error, this lab was a successful
  one.

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Whiteboard the Lab
After analyzing the lab and Other stuff, we then
whiteboard The lab. White boarding the lab Is to
use a white board like That one on the picture
at the Left to write all our data, setup, Math
model, and graph to have A talk with the class to
discuss What the slope, y-intercept, and Other
concepts means.
The whole class gives in and comes out with the
best answer, but sometimes We the students get
stuck and come up With the right answer so
teacher come up to solve and finalize the
problem.
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Conclusion

• First of all, this lab was very easy to construct
  and the percent error should not exceed 2 or 4
  percent. The reason I said that is because we
  didnt have to do much in this lab but to measure
  the string and move it. We didnt have to used a
  stopwatch or count the period, the photo gate and
  the computer did it all for us. Though we did
  say that the angle at which we drop the metal
  piece does not matter because gravity will pull
  it at 9.8m/s2 no matter where it is.
  (Acceleration doesnt depend on the mass of the
  metal in free fall) But couple of reason why we
  said it wasnt a good idea to drop it at such a
  higher angle is that it might wobble if we went
  to high as in the metal piece would actually drop
  straight down and that would cause the wobbling.
  That would be one of the errors. Another human
  error I thought of was if you let it drop at a
  higher angle, it would tends to go faster. For
  if it goes faster, it is sometime hard to aim for
  the metal piece to go through the small gap of
  the photo gate because it sometimes tends to
  travel in an ellipse. Or that for the higher
  speed, the photo gate might not be so efficient
  with it because maybe a photo gate as such wasnt
  made to handle higher velocity. Otherwise thats
  most of the error that happened in this lab,
  which we never had problems with.

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Important equations to remember
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Experiment has Ended