wrose75

08-26-2005, 01:48 AM

Dai,

There definitely is practical value in knowing the direction of the torque

vector. Torque tends to cause rotation. The direction of the torque vector

is the axis of the rotation (and as you mentioned, the direction of rotation

about the axis is determined using the right hand rule). By knowing the

torque vector you can compare it to the desired axis of rotation to see how

well they match. Examples: 1. If you are using a wrench on a nut, you want

the torque vector aligned with the shaft of the screw to have the most

effect on the nut and the least chance of bending the shaft. 2. Does the

torque about the knee joint correspond to the normal anatomical axis of

rotation of the joint? 3. An ice skater working on jumps could benefit from

knowing how well the direction of the pre-takeoff torque vector corresponds

to the desired in-flight axis of rotation.

Bill Rose

University of Delaware

----- Original Message -----

From: "Dai Nishikawa"

To:

Sent: Friday, August 26, 2005 12:09 AM

Subject: [BIOMCH-L] question about direction of torque vector

>I have a simple question regarding the direction of torque vectors and I

>would appreciate if anyone give me tips: I understand torque vectors are

>orientated perpendicular to the plane in which the moment arm and force

>vectors exist and the right-hand-thumb rule is used to tell whether it is

>orientated at the right angle into or out of the page. My question is: what

>is the practical use of knowing the direction of torque vectors?; Are they

>just concepts which faciltate the understanding of dynamic forces?

>

> Regards

> Dai Nishikawa

There definitely is practical value in knowing the direction of the torque

vector. Torque tends to cause rotation. The direction of the torque vector

is the axis of the rotation (and as you mentioned, the direction of rotation

about the axis is determined using the right hand rule). By knowing the

torque vector you can compare it to the desired axis of rotation to see how

well they match. Examples: 1. If you are using a wrench on a nut, you want

the torque vector aligned with the shaft of the screw to have the most

effect on the nut and the least chance of bending the shaft. 2. Does the

torque about the knee joint correspond to the normal anatomical axis of

rotation of the joint? 3. An ice skater working on jumps could benefit from

knowing how well the direction of the pre-takeoff torque vector corresponds

to the desired in-flight axis of rotation.

Bill Rose

University of Delaware

----- Original Message -----

From: "Dai Nishikawa"

To:

Sent: Friday, August 26, 2005 12:09 AM

Subject: [BIOMCH-L] question about direction of torque vector

>I have a simple question regarding the direction of torque vectors and I

>would appreciate if anyone give me tips: I understand torque vectors are

>orientated perpendicular to the plane in which the moment arm and force

>vectors exist and the right-hand-thumb rule is used to tell whether it is

>orientated at the right angle into or out of the page. My question is: what

>is the practical use of knowing the direction of torque vectors?; Are they

>just concepts which faciltate the understanding of dynamic forces?

>

> Regards

> Dai Nishikawa