How Do Shockwaves Form Around Supersonic Bullets?

TL;DR

Shockwaves form around supersonic bullets due to changes in air density that bend light, visible through a Schlieren setup. The angle of these shockwaves, known as the Mach Angle, provides a way to calculate bullet velocity. Subsonic bullets can also create unique airflow patterns, demonstrating that even below the speed of sound, distinct shockwaves can be detected.

Transcript

• Hey, it's me Destin. Welcome back to "Smarter Every Day." As long as I've understood the physics, I've wanted to visualize the Shock Wave on the front of a super sonic bullet. But the problem with doing this, is you have to have access to some pretty expensive optical hardware. Which is why I'm pretty excited about this giant 16" parabolic mirror... Read More

Key Insights

• 🫢 The Schlieren setup allows for the visualization of shock waves on supersonic bullets by detecting changes in air density.
• ✈️ Shock waves are caused by differences in air density, resulting in the bending or refraction of light passing through.
• 🚄 The speed of the bullet and the environment it passes through determine the formation and characteristics of the shock waves.
• 🫢 The angle of the shock wave, known as the Mach Angle, can be used to measure the velocity of a bullet.
• 🫢 Subsonic bullets can still create supersonic airflow and exhibit unique shock wave patterns.
• 🫢 The Schlieren setup can also capture the shock waves emitted by the muzzle blast of weapons.
• 🫢 Revolvers tend to leak shock waves out of the side due to the design and structure of the weapon.

Questions & Answers

Q: How does the Schlieren setup work in capturing images of shock waves on super sonic bullets?

The Schlieren setup uses a point source of light, a mirror, and a camera to detect changes in air density caused by the shock waves. Light is bent as it passes through different types of air, creating shadows that can be observed and recorded.

Q: What is the purpose of the 16" parabolic mirror in the setup?

The parabolic mirror allows for the manipulation and focusing of light, enabling the detection of even subtle changes in air density caused by shock waves.

Q: What causes the different shock waves observed in the video?

The initial shock wave is believed to come from the bullet itself, while the subsequent shock waves are likely a result of reflections from the surface beneath the mirror, such as the plywood table and the concrete floor.

Q: Why do subsonic bullets exhibit different shock wave patterns compared to supersonic bullets?

Subsonic bullets, although traveling at speeds less than the speed of sound, can still create supersonic airflow around them due to changes in air density. This phenomenon, known as a Normal Shock, results in different shock wave patterns.

Summary & Key Takeaways

• The video showcases the use of a Schlieren setup to capture images of shock waves on supersonic bullets.

• By manipulating light and detecting shadows, the setup allows for the visualization of shock waves caused by differences in air density.

• The video explains the formation of shock waves and shows how they vary depending on the speed of the bullet and the surrounding environment.