Help: The physics behind the throws of judo?

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In summary, the conversation revolves around a high school senior wanting to write an essay on the physics and biomechanics of judo and its throws. They are struggling to find resources and are looking for help on how to approach the topic. Suggestions are made to break down the moves into smaller parts and analyze them from a physics perspective, using concepts such as force, momentum, lever, center of balance, gravity, and torque. The importance of minimizing effort in judo and the role of biomechanics in throws are also discussed.
  • #1
WizErnest
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I have been wanting to do an essay(4000 words) on the physics/biomechanics of judo and its throws. The only problem is I don't where to begin. Any help would be appreciated!
 
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  • #2
WizErnest said:
The only problem is I don't where to begin.
Google?
 
  • #3
A.T. said:
Google?

Only problem is I have been searching for 2 days and I'm still not sure how everything fits together. The documents and sites that might be able to help me are behind pay walls so...

I'm high school senior and I have been taking some physics and biology courses at school. So I have some basic ideas on how they interact to from biomechanics. Like how the forearm is lever and when the bicep contracts it applies a force to the tendons that connect to the forearm causing torque and the movement of your arm.
 
  • #4
A.T. said:
Google?

That kind of answer dosent really seem to help things, I think OP would have already thought of that before coming here to post.

Why not try to set out a series of questions about a throw? As in, "In order to throw a 75Kg opponent in a parabola over his shoulder, how much work would the judo master have to do?

Then you could try to build 3 or 4 successively more intricate models of a human as both a mass and a lever.

Maybe try to compare the energy the judo master actually expends compared to the most ideal situation?
 
  • #5
WizErnest said:
I have been wanting to do an essay(4000 words) on the physics/biomechanics of judo and its throws. The only problem is I don't where to begin. Any help would be appreciated!

irishhockey said:
That kind of answer dosent really seem to help things, I think OP would have already thought of that before coming here to post.

It's a fine answer in this case. The PF rules (under Site Info at the top of the page) require that posters show some effort when asking schoolwork-type questions.

@WizErnest -- Welcome to the PF. Have you taken Judo? If so, for how long and what belt level are you currently at?

The Physics of Judo is not just calculating how high parabolic paths reach. The whole point of Judo is to minimize your effort in throwing, choking and pinning your opponent. "Balance, Momentum, Leverage" is one of the key mantras in Judo...
 
  • #6
berkeman said:
It's a fine answer in this case. The PF rules (under Site Info at the top of the page) require that posters show some effort when asking schoolwork-type questions.

Sorry, I just read it in my head as kind of talking down.

Back on topic, maybe trying to model two whole people interacting is a lot (I'm a Sr physics major and that sounds daunting to me). Break things into little bits.
 
  • #7
Why not try to set out a series of questions about a throw? As in, "In order to throw a 75Kg opponent in a parabola over his shoulder, how much work would the judo master have to do?

Judo Novice - he would try try with all his might and not get to throw anybody.
Judo Master - very little work as he knows that he will use the opponents momentum, centre of mass being off balance, and gravity to complete a move to success.
 
  • #8
256bits said:
Judo Novice - he would try try with all his might and not get to throw anybody.
Judo Master - very little work as he knows that he will use the opponents momentum, centre of mass being off balance, and gravity to complete a move to success.

This is true, but why not compare a judo master to a simple machine?

* Also, I never meant to bring skill into the mix, I was just using judo master before beacuse it sounds better than "practitioner of judo" or something.
 
Last edited:
  • #9
WizErnest said:
Only problem is I have been searching for 2 days and I'm still not sure how everything fits together. The documents and sites that might be able to help me are behind pay walls so...

I'm high school senior and I have been taking some physics and biology courses at school. So I have some basic ideas on how they interact to from biomechanics. Like how the forearm is lever and when the bicep contracts it applies a force to the tendons that connect to the forearm causing torque and the movement of your arm.

One basic move in Judo is as follows:
You and your opponent are holding on to each other and doing various shifts in position. You opponent suddenly pushes against you trying to unbalance you, thinking he will kick a foot out as you step back. Being a worthy Judo athlete, what do you do?
You pull on his upper body, while at the same time dropping down, and sticking a foot ( or two if you are so inclined at the moment ) at his abdomen. What happens - your opponent is carried over you and lands on his back, and you, while that is occurring, grab onto the end of an arm, place a foot over his body and one under the arm for a pin winning the match and the title.

Physics -
Force - Newton's law - him pushing and then you pushing.
Momentum - his forward movement continues throughout the throw.
Lever - your foot is being used as a fulcrum
Centre of balance - he cannot obtain a footing to re-balance himself
Gravity- you dropping down, and him falling down on his back.
Torque - he has rotated 180 degrees
Force - pinning the arm and body disallows him to upright himself. Here you are using your body weight ( again gravity ) and prohibiting him from using any leverage to right himself.
It could be I missed something.

Try to see if you can evaluate the physics of other throws in a similar manner, such as the hip throw, or just a kick out of a leg.

From a biomechanical point of view, I am not sure how to fit a description in there. Certainly, strength and size do not matter as much as some other factors.
 
  • #10
Let's let the OP WizErnest reply before we give much more help here... :smile:
 
  • #11
berkeman said:
It's a fine answer in this case. The PF rules (under Site Info at the top of the page) require that posters show some effort when asking schoolwork-type questions.

@WizErnest -- Welcome to the PF. Have you taken Judo? If so, for how long and what belt level are you currently at?

The Physics of Judo is not just calculating how high parabolic paths reach. The whole point of Judo is to minimize your effort in throwing, choking and pinning your opponent. "Balance, Momentum, Leverage" is one of the key mantras in Judo...

I'm a white belt and have doing it for about month now.
 
  • #12
Sorry, I've been away for a long time. I recently purchased a book: "The Secrets of Judo", which is very heavy on the mechanics and physics behind judo. So far I've got to stability and the mechanics of unbalancing an opponent, usually by moving is center of gravity beyond his/her base of support.
 
  • #13
berkeman said:
The whole point of Judo is to minimize your effort in throwing, choking and pinning your opponent. "Balance, Momentum, Leverage" is one of the key mantras in Judo...
In contests between highly skilled opponents (like the olympics), there are weight classes since strength and weight are significant factors when both opponents are highly skilled. In the few times I've seen judo events on the olympics, its seems like there's a lot of effort involved in all the moves.
 
  • #14
@Wiz
You have chosen the project because you like both the Judo and the Physics, and I can understand it's an attractive idea for you. The big snag is that Judo involves a very complicated set of moves, involving all your muscles and skeleton and a load of varied Physics ideas. You have definitely gone in off the deep end with this one and I would recommend (along with others) that you try to break the thing down into small parts and look at some chosen parts in detail. Write a list of all the mechanics topic you know and put the aspects of Judo that it could be relevant to next to each topic. Pick just one (the one with most in it, perhaps). That will be quite enough to be dealing with!
 
  • #15
sophiecentaur said:
@Wiz
You have chosen the project because you like both the Judo and the Physics, and I can understand it's an attractive idea for you. The big snag is that Judo involves a very complicated set of moves, involving all your muscles and skeleton and a load of varied Physics ideas. You have definitely gone in off the deep end with this one and I would recommend (along with others) that you try to break the thing down into small parts and look at some chosen parts in detail. Write a list of all the mechanics topic you know and put the aspects of Judo that it could be relevant to next to each topic. Pick just one (the one with most in it, perhaps). That will be quite enough to be dealing with!

Good Advice! Thank you all!
 
  • #16
Don't forget to stay in touch when you have made your choices.
 
  • #17
sophiecentaur said:
Don't forget to stay in touch when you have made your choices.

yes, please, I'm quite interested.
 

FAQ: Help: The physics behind the throws of judo?

1. How does the physics of force and motion play a role in judo throws?

The throws in judo rely heavily on the principles of force and motion. In order to execute a successful throw, a judoka must apply force to their opponent and manipulate their center of mass to disrupt their balance. This requires an understanding of Newton's Laws of Motion and the concept of momentum.

2. How does a judoka use leverage to perform throws?

Leverage is a key element in judo throws. By using their opponent's own force and momentum against them, a judoka can maximize the effect of their throws. This is achieved by positioning their body in a way that allows them to use their opponent's weight and movement to their advantage.

3. How does the distribution of weight affect the outcome of a judo throw?

In judo, the distribution of weight is crucial in executing successful throws. By shifting their opponent's weight to one side, a judoka can create an imbalance and make it easier to throw them. Similarly, a judoka must maintain their own balance and distribute their weight properly in order to execute a throw with maximum force.

4. What role does momentum play in judo throws?

Momentum is a key factor in judo throws. In order to successfully throw an opponent, a judoka must use their opponent's momentum and apply force in the opposite direction. By doing so, they can disrupt their opponent's balance and control their movement to execute a powerful throw.

5. How does the concept of torque apply to judo throws?

Torque, or the rotational force, is an important aspect in judo throws. By using their body and limbs as levers, a judoka can generate torque and apply it to their opponent to execute a throw. This requires precise technique and control, as well as an understanding of the principles of torque and rotational motion.

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