The Mathematics of the Karate Chop - Professor John D. Barrow

TL;DR

Breaking wooden planks and bricks in martial arts requires precise technique, high impact speed, and short contact time.

Transcript

well you know what I'm talking about here I'm not going to demonstrate it um because I couldn't uh so it's a sort of party piece of um of uh karate black belts of having a stack of planks for example or a brick or bricks and breaking them well let's have a look at the numbers here um the key to doing this by the way and why you and I if we're not t... Read More

Key Insights

• 🥋 Precise technique and not decelerating at the moment of impact are crucial for successfully breaking wooden planks and bricks in martial arts.
• 🍳 Breaking multiple thinner planks sequentially is easier than breaking one thick block, as it requires less force.
• 🚄 Top karate exponents can generate enough force to break wooden planks and bricks due to the combination of high impact speed and short contact time.
• 🐎 The speed at impact and the short time interval of speed change contribute to the acceleration necessary for breaking the objects.
• 💩 Slowing down the arm before impact results in hitting the object with almost zero acceleration and potential injury.
• 🥋 Breaking wooden planks and bricks in martial arts is a skill that requires practice, technique, and understanding of the physics involved.
• 🚄 The mass of the arm moving at high speed plays a significant role in the transfer of momentum and the force applied to break the objects.

Questions & Answers

Q: Why do most people fail at breaking wooden planks and bricks?

Most people fail because they decelerate at the moment of impact, while the technique requires maintaining maximum acceleration throughout the strike.

Q: Why is breaking multiple thinner planks easier than breaking one thick block?

Breaking thinner planks involves severing a slice of atomic bonds, which requires less force compared to breaking a thicker block with more atomic bonds.

Q: How fast does a top karate exponent's hand need to move to break the top plank?

A top karate exponent's hand needs to move at a speed of at least 7 m/s to break the top plank successfully.

Q: What is the relationship between acceleration and contact time in breaking wooden planks?

The acceleration required to break wooden planks is directly related to the contact time with the wood, which is typically very short, around 5 milliseconds.

Summary & Key Takeaways

• Breaking wooden planks and bricks is a common demonstration in martial arts, showcasing the skill and technique of black belts.

• The key to breaking these objects is hitting them with maximum acceleration, which requires precise technique and not decelerating at the moment of impact.

• Breaking multiple thinner planks sequentially is easier than breaking one thick block, as it requires breaking a slice of atomic bonds in each plank.