Simple Pendulum Lab Report
Candidate Number:
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IBDP PHYSICS Internal Assessment
Student: Pascal BLAISE – Date: 10 December 2009
Supervisor: Mr. FOUCAULT – International School of Pisa
“To what extent does the length of the string affect the period of a simple pendulum?”
IBDP PHYSICS Internal Assessment – The Simple Pendulum
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INTRODUCTION
The original aim for this invesigation was to “investigate the simple pendulum”. There are many variables one could look into, such as displacement, angle, damping, mass of the bob etc. The most interesting variable, however, is the length of the swinging pendulum. The relationship between the length and the time for one swing (the period) has been researched for many centuries, and has allowed famous physicists like Isaac Newton and Galileo Galilei to obtain an accurate value for the gravitational acceleration ‘g’. In this report, we will replicate their experiment, and we will try to find an accurate value for ‘g’ here in Pisa. We will then compare this value with the commonly accepted value of 9.806 m/s2
[NIST, 2009]
A CLOSER LOOK AT OUR VARIABLES
In this investigation, we varied the length of the pendulum (our independent variable) to observe a change in the period (our dependent variable). In order to reduce possible random errors in the time measurements, we repeated the measurement of the period three times for each of the ten lengths. We also measured the time for ten successive swings to further reduce the errors. The length of our original pendulum was set at 100 cm and for each of the following measurements, we reduced the length by 10 cm. THEORY
A simple pendulum performs simple harmonic motion, i.e. its periodic motion is defined by an acceleration that is proportional to its displacement and directed towards the centre of motion. It can be shown that the period T of the swinging pendulum is proportional to the square root of the
1
2
2
3
0
7
IBDP PHYSICS Internal Assessment
Student: Pascal BLAISE – Date: 10 December 2009
Supervisor: Mr. FOUCAULT – International School of Pisa
“To what extent does the length of the string affect the period of a simple pendulum?”
IBDP PHYSICS Internal Assessment – The Simple Pendulum
9
INTRODUCTION
The original aim for this invesigation was to “investigate the simple pendulum”. There are many variables one could look into, such as displacement, angle, damping, mass of the bob etc. The most interesting variable, however, is the length of the swinging pendulum. The relationship between the length and the time for one swing (the period) has been researched for many centuries, and has allowed famous physicists like Isaac Newton and Galileo Galilei to obtain an accurate value for the gravitational acceleration ‘g’. In this report, we will replicate their experiment, and we will try to find an accurate value for ‘g’ here in Pisa. We will then compare this value with the commonly accepted value of 9.806 m/s2
[NIST, 2009]
A CLOSER LOOK AT OUR VARIABLES
In this investigation, we varied the length of the pendulum (our independent variable) to observe a change in the period (our dependent variable). In order to reduce possible random errors in the time measurements, we repeated the measurement of the period three times for each of the ten lengths. We also measured the time for ten successive swings to further reduce the errors. The length of our original pendulum was set at 100 cm and for each of the following measurements, we reduced the length by 10 cm. THEORY
A simple pendulum performs simple harmonic motion, i.e. its periodic motion is defined by an acceleration that is proportional to its displacement and directed towards the centre of motion. It can be shown that the period T of the swinging pendulum is proportional to the square root of the
References: National Institute of Standards and Technology. 2009. The NIST Reference on Constants, Units and Uncertainty [Online] Available at: http://physics.nist.gov/cgi-bin/cuu/Value?gn [Accessed 8 December 2009] Practical Physics. 2009. The Swinging Pendulum [Online] Updated 22 October 2007. Available at http://www.practicalphysics.org/go/Experiment_480.html [Accessed 8 December 2009] Flightpedia. 2009. Pisa Airport PSA [Online]. Available at http://www.flightpedia.org/airports/pisa-italygal-galilei-psa.html [Accessed 8 December 2009]