Calculating G: Simple Pendulum Experiment, problems?

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SUMMARY

The discussion focuses on the challenges of calculating gravitational acceleration (g) using a Simple Pendulum experiment with high precision (+/-0.005). Key issues identified include the effects of large displacement on drag forces, the assumption of small angles in the sqrt(l/g) equation, and the importance of accurately measuring the pendulum length to the center of gravity (CG) while accounting for potential elongation due to load and temperature changes. These factors are critical for achieving precise measurements in the experiment.

PREREQUISITES
  • Understanding of pendulum mechanics and the formula g = 4π²L/T²
  • Knowledge of experimental physics and precision measurement techniques
  • Familiarity with the concept of center of gravity (CG) in pendulum systems
  • Awareness of environmental factors affecting experimental results, such as temperature
NEXT STEPS
  • Research methods to minimize drag effects in pendulum experiments
  • Learn about the implications of the small angle approximation in pendulum motion
  • Explore techniques for precise length measurement in pendulum setups
  • Investigate the impact of temperature on material properties in experimental physics
USEFUL FOR

Physics students, experimental physicists, and educators conducting precision measurements in gravitational studies will benefit from this discussion.

SimonChen
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I need to experimentally calculate gravity (g) with an extreme precision (+/-0,005). We thought about trying an Atwood Machine but too many problems were related to it so we've decided to switch to an Simple Pendulum (with a very long L). What are the problems related to the Simple Pendulum experiment?

Thanks!
 
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1. You should not give it a large displacement because you'll be affected by drag on the bob and string.

2. Inherent in the sqrt(l/g) equation is the assumption that sin(theta)=theta for small angles.

3. Measure the length to the CG with the bob attached and in vertical position so that any elongation (due to load) on the string will be noted. This should be done at the start in case there are temperature changes affecting the length if tests are not done all in one session.
 

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