Before we dive into the subject, we must refresh our memory on basic physics. Isaac Newton divided the laws of motion into 3 separate laws.
- 1st Law of Motion (Inertia)
- 2nd Law of Motion (Force)
- 3rd Law of Motion (Action vs Reaction)
These laws put into perspective the relationship between forces acting on a mass and the motion of this mass. Every mass or body must unwittingly check these rules in order to create motion. Think of something simple – like throwing a ball.
Throwing a ball, without first winding your arm back, creates very little energy and the ball will not travel too far. When you wind your arm back and propel it forward, you create inertia on the ball, which makes it travel much further. This is the 1st Law of Motion in its simplest form.
The ball itself and alone can not generate enough energy to move itself. For the ball to move, a force most be applied to it. This ball will continue moving for as long as it has momentum and velocity, thus satisfying the 2nd Law of Motion.
Lastly, the part that most people fail to see, the 3rd Law of Motion. For the ball to be able to travel forward, there must be a force of equal value applied in the opposite direction. We do this every day to move our own bodies, and gravity is our tool for the job. When you throw the ball, you are grounded by gravity, which gives you the ability to move something forward – in this case, the ball. To help you realize this, look at videos of astronauts in zero gravity and watch how much they struggle to throw something to each other.
Yes, What About Judo?
All Judo throws also consist of 3 parts which allow you to throw a person – Kuzushi (Balance), Tsukuri (Entry), and Kake (Execution). Now, consider that this person is also heavier than the ball in our last example. It is an animate body that can use logic and reason and make decision of its own, unlike our spherical friend. And in most cases, this person is also trained to counter your use of physics! Because of this, we must dramatically enhance the way we use the Three Laws of Physics to achieve Kake.
Everyone who has done Judo for a few days has heard that Kuzushi is the most fundamental and crucial part of a throw, but don’t think of it as just something you need to do to disrupt their balance, it is also an ingredient to a powerful throw. If you ever try to throw a person who is firmly grounded, you would notice it is incredibly difficult! However, when you get the person moving in different directions, you create a state of inertia that reduces the amount of strength you will need to execute the throw. This is how Judo implements the 1st Law of Motion.
Once you have decided to attack with your desired throw, a necessary amount of Force is applied in the direction of the throw. Sometimes, this force comes in the form of posture, lift & pull, reap, drop, or any technique that allows you to maintain the acceleration that was created by inertia. This is the 2nd Law of Motion in action.
And lastly, action vs reaction. Almost every judoka will agree that their first throw is commonly a setup throw that causes a reaction. This expected reaction creates inertia and makes the chained throw more effective. The initial attack causes the Uke to defend. Depending on the throw being used, the Uke will be generating a force in the opposite direction from yours. This is an ideal window of time to use the inertia generated to project the Uke in that direction.
Throwing someone who doesn’t want to be thrown is probably one of the hardest things that anyone could do to someone else. This is not exclusive to Judo. The concept explained above can also be found in Wrestling, Sambo, and even in Brazilian Jiu-Jitsu! Think of a sweep or reversal as a throw, and you will notice these laws are also in effect.