Path: chuka.playstation.co.uk!news From: "Jon Prestidge (Moose)" Newsgroups: scee.yaroze.programming.3d_graphics Subject: angular acceleration Date: Thu, 2 Dec 1999 12:51:55 -0000 Organization: PlayStation Net Yaroze (SCEE) Lines: 41 Message-ID: <825q0v$gu11@chuka.playstation.co.uk> NNTP-Posting-Host: modem-6.palladium.dialup.pol.co.uk X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 5.00.2014.211 X-MimeOLE: Produced By Microsoft MimeOLE V5.00.2014.211 Is anyone familiar with the formula to calculate angular acceleration from torque and moment_of_inertia ... or, more to the point, the appropriate units to use? I think it is:- angular_acceleration = torque / moment_of_inertia ... if torque is in Newton_metres and moment_of_inertia is in Kg * metres_squared, then what is angular_acceleration in? Is it in radians_per_second_per_second ? I'm just a bit sceptical it could be that simple! If so does this example look about right?... I'm working through an example of lifting-up my straight arm as fast as I can. I reckon the max torque of my sholder in that direction is about 68Nm and the moment_of_inertia of my straight arm about the axis of my sholder is about 0.937 Kg * m_squared. So... angular_acceleration = 68 / 0.937 = 72.57 so if it was 72.57 radians_per_second_per_second it would equate to 4158 degrees (or for the playstation 47308 1/4096ths) So (ignoring gravity) I could lift my straight arm from down by my side upto horizontal, which is about a quarter arc:- ( if I could do 72.57/1.57 = 46.199 quarter arcs per_second_per_second ) I could achive the quater arc in 0.022 of a second? That seems too quick. Jon Prestidge P.S. I've got a list I've compiled of typical max torques for each joint in the body, which any one is welcome to ( just mail me jon@surfed.to ). Be warned though, it is not tried and tested data, it is data from me and bathroom scales and a few sprained muscles.