Chapter 13: Problem 12
In the measurcment of \(g\) using simple pendulum the time taken for 30 oscillations is \((61.2 \pm 1.3) \mathrm{s}\) and cffective length of pendulum is \((1.00 \pm 0.01) \mathrm{m} .\) The value of \(g\) with error limits is: (a) \((9.80 \pm 0.2) \mathrm{m} / \mathrm{s}^{2}\) (b) \((9.81 \pm 0.47) \mathrm{m} / \mathrm{s}^{2}\) (c) \((9.49 \pm 0.1) \mathrm{m} / \mathrm{s}^{2}\) (d) \((9.49 \pm 0.47) \mathrm{m} / \mathrm{s}^{2}\)
Short Answer
Step by step solution
Calculate Time Period
Determine the Uncertainty in Time Period
Use the Formula for Acceleration Due to Gravity
Calculate \( g \)
Determine the Uncertainty in \( g \)
Calculate the Final Error in \( g \)
Identify the Correct Option
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Oscillation
This continual to-and-fro motion is surprisingly consistent and can be described by physics.
- Amplitude: The maximum extent of the swing from the central (equilibrium) position.
- Frequency: How often the pendulum completes an oscillation in a given time, typically measured in Hertz (Hz).
- Time Period: The time it takes for one complete oscillation.
Gravitational Acceleration Measurement
\[ g = \frac{4\pi^2 L}{T^2} \]
Here, L is the length of the pendulum, and T is the time period for one oscillation. By measuring how long it takes the pendulum to complete a set number of oscillations, we can calculate T and subsequently determine g.
- The formula comes from mathematical physics, where the combination of constants \( 4\pi^2 \) ensures appropriate unit conversion.
- This method provides a relatively simple approach to measuring gravitational acceleration due to its reliance on basic observations.
Error Propagation
- The formula for relative error in g is: \[ \frac{\Delta g}{g} = \sqrt{\left( \frac{\Delta L}{L} \right)^2 + \left( 2 \times \frac{\Delta T}{T} \right)^2} \]
- This formula comprehensively evaluates how uncertainties in both L and T combine to affect the accuracy of g.
- It's crucial to use accurate measurements and minimize sources of error to improve the reliability of the calculated gravitational acceleration.
Time Period Calculation
\[ T = \frac{t}{n} \]
Here, \( t \) is the total time, and \( n \) is the number of oscillations. In our exercise, 30 oscillations took 61.2 seconds, resulting in a time period of 2.04 seconds.
- Knowing the time period allows physicists to relate the pendulum's physical properties to gravitational acceleration.
- Even small errors in timing can influence the outcome, highlighting the need for precise timekeeping.