Lecture Notes

Introduction

Pendulum Description: Mass (m), Length (L).
Period of a Pendulum: Derived as ( T = 2\pi \sqrt{\frac{L}{g}} ).
- ( g ) = gravitational acceleration (approximately 9.80 m/s² in Boston).
- Period is independent of amplitude and mass of the bob.
Demonstration: Period calculated for L = 1m gives T = 2 seconds.
Measurement and Accuracy:
- Pendulum mass: 15.5 kg.
- Length: 5.21 meters (with 1% uncertainty).
- Predicted period: 4.58 ± 0.02 seconds.
- Challenges in measurement due to human reaction time.

Potential Energy: ( mgh ) where ( h ) is height.
Kinetic Energy: ( \frac{1}{2}mv^2 ).
Energy Transfer: Total energy is conserved, converted between potential and kinetic.
Pendulum Conservation: Height at release equals height on return (no higher).

Building Demolition: Use of potential energy converted to kinetic energy.
Personal Experiment: Demonstrated conservation of energy by standing in the path of a pendulum.

White Light Composition: Contains all rainbow colors.
Rayleigh Scattering: Blue light scattered more than red.
- Scattering proportional to ( \frac{1}{\lambda^4} ).
- Blue light wavelength ~1.5x lower than red.
Demonstrations: Cigarette smoke and lung experiment.
- Blue light scatters from smoke; white light scatters from larger particles.

Rayleigh Scattering Explanation: Sky appears blue due to scattering of blue light by small particles in the atmosphere.
Sunset and Sunrise: Red due to longer path through the atmosphere, scattering out shorter wavelengths.
Demonstration: Use of sodium thiosulfate and sulfuric acid to simulate blue sky and red sunset in the lecture hall.

Questions and Interactions: Engaged audience with questions on pi, personal experiences, and career inspirations.
Advice to Students: Passion in physics is essential; bad experiences often due to poor teaching.