Calculating Angular Acceleration in Judo Foot-Sweep Move

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Homework Help Overview

The problem involves calculating the angular acceleration of a judo opponent during a foot-sweep move, considering various forces and moments acting on him. The subject area includes dynamics and rotational motion.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the application of Newton's second law of rotation and the concept of torque. There are attempts to express the relationship between torque, rotational inertia, and angular acceleration. Some participants express uncertainty about how to begin the calculations and the definitions involved.

Discussion Status

The discussion is ongoing, with participants seeking clarification on the concepts and equations relevant to the problem. Some guidance has been offered regarding the use of Newton's second law of rotation, but there is no consensus on the approach yet.

Contextual Notes

Participants note their beginner status in physics, which may affect their understanding of the problem setup and the relevant equations. There is a mention of specific values such as mass, distance, and force, but the implications of these values are still being explored.

Batz74
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Homework Statement


In a judo foot-sweep move, you sweep your opponent's left foot out from under him while pulling on his gi (uniform) toward that side. As a result, your opponent rotates around his right foot and onto the mat. Figure shows a simplified diagram of your opponent as you face him, with his left foot swept out. The rotational axis is through point O. The gravitational force him effectively acts at his center of mass, which is a horizontal distance d = 28 cm from point O. His mass is 70 kg, and his rotational inertia about point O is 65 kg·m2. What is the magnitude of his initial angular acceleration about point O if your pull on his gi is (a) negligible and(b) horizontal with a magnitude of 300 N and applied at height h = 1.4 m? Assume free-fall acceleration to be equal to 9.81 m/s2.


Homework Equations



Newtons' second law of rotation


The Attempt at a Solution

 
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Welcome to PF!

Hi Batz74! Welcome to PF! :wink:

Show us what you've tried, and where you're stuck, and then we'll know how to help! :smile:
 
Hi, and thank you. I actually have NO idea where to start:cry: i am beginner in my physics course..
 
start by writing out Newton's second law of rotation
 
T = Ia ?

So, T = (70x14^2) x a
 
i don't understand :redface:
 
neither do I -_- so am i looking for rotational inertia?
 

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