Calculating Angular Acceleration in Judo Foot-Sweep Move

[Batz74]

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

 

[tiny-tim]

Welcome to PF!

Hi Batz74! Welcome to PF!

Show us what you've tried, and where you're stuck, and then we'll know how to help!

 

[Batz74]

Hi, and thank you. I actually have NO idea where to start i am beginner in my physics course..

 

[tiny-tim]

start by writing out Newton's second law of rotation

 

[Batz74]

T = Ia ?

So, T = (70x14^2) x a

 

[tiny-tim]

i don't understand

 

[Batz74]

neither do I -_- so am i looking for rotational inertia?