Feynman Lectures Simplified 1D: Sound, Waves, Angular Momentum, Symmetry & Vision

Guide to the Cosmos
Making the Wonders of our Universe

Accessible to Everyone

Robert L. Piccioni, Ph.D.

Feynman Lectures

Feynman Simplified
ebook series
Feynman Simplified
Award winning books
Shop Now
About Dr. Piccioni
Free Videos
mailbox Newsletter SignUp

1D: Sound, Waves,
Angular Momentum,
Symmetry & Vision

Feynman Simplified 1D covers a quarter of Volume 1, the freshman course, of The Feynman Lectures on Physics. The topics we explore include:
  •     Angular Momentum
  •     Moments of Inertia
  •     Rotations in Three-Dimensions
  •     Sound & Beat Frequencies
  •     Modes & Harmonics
  •     Fourier Series & Transforms
  •     Complex Waves
  •     Symmetry Properties of Natural Laws


Bow Waves

Bow waves are created by a source moving faster than the wave velocity. Consider the example of a jet flying faster than the speed of sound in air. At each point P along the jet’s path, the jet compresses the air in front of it, creating a pressure wave that spreads outward in all directions at the speed of sound, cs.

Figure 46-1 shows the crests of pressure waves emitted at equally spaced times. All such waves will be tangent to a common line, thus creating a bow wave.

Bow Wave

Figure 46-1 Jet (grey) Creating Bow Wave
An Intense Conical Wave With Half-Angle θ

Feynman notes that a bow wave is created whether or not the jet itself makes any sound — sound is created by the mere act of moving through air faster than the speed of sound. The next figure clearly illustrates a bow wave coming from a bullet.
Sock wave from bullet
Bullets are not sources of sound in and of themselves; it is their high-speed passage through air that creates sound waves.

for $7.99

Click on one
of the following

Feynman Lectures
Simplified 1D:
Angular Momentum...

Barnes & Noble


See all the
books in the