[Gismo R]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (dsjunkie @ Mar. 14 2002,01:03)</td></tr><tr><td id="QUOTE">ok well i was reading the big post by wherezmytofu (which i must say is good, you know your stuff man) and it brought up an old issue i had w/ a post a few days back on torque and power, the physics thereof....

torque is the dot product of the force applied and the radius of the object, and power is the dot product of the force and the velocity.

now i know the force is the force of the explosion of the air/gas mixture in the cylinder....and the radius is the radius of the crank...and velocity is rpms (but i'm not concerned w/ that right now....just the torque aspect of it)

ok the dot product has to do with vectors, correct?....example, the dot product of (u,v) and (x,y) is ux + vy, similarly the dot product of (u,v,w) and (x,y,z) is ux + vy + wz

now here's my question how do you convert a radius to a vector?

btw if you want IM me at dsjunkie...i'm on a lot (mainly at night)</td></tr></table><span id='postcolor'>
maddindian is correct, it's the cross product of the radius [r] and the force [F].
To convert the radius to a vector you use

r*sin(theta) for the Y value
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;and
r*cos(theta) for the X value.
&nbsp; (theta being the angle between the X-axis and r)

To covert to 3D (hence x,y,z values), life gets a little complicated. You would need two angles, one from the Y or X axis and another from the Z axis. But basically the same idea as in 2D.

The cross product of two vectors is basically the product of the magnitudes of the vectors times sin(theta), where theta is the angle between the two vectors.

So when talking about Torque, here is the equation.

T = F x r &nbsp; &nbsp; &nbsp; = &nbsp; &nbsp; &nbsp; T = |F| sin(theta) |r|