# Thread: Torque? I need concept!

1. I know well that torque is a vector product and it is a kind of work done which is parallel to the axis of rotation.But,how can torque passes through z-axis whereas it's compoment is along x and y axis?If it is true then I should feel repulsion on my finger when touch the centre tips of rotating body since torque must passes through axis.But I don't feel any repulsion on my finger,why?Your interest in my question will obviously benifit me.So,thankyou!

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3. Originally Posted by sagarkaran
I know well that torque is a vector product and it is a kind of work done which is parallel to the axis of rotation.But,how can torque passes through z-axis whereas it's compoment is along x and y axis?If it is true then I should feel repulsion on my finger when touch the centre tips of rotating body since torque must passes through axis.But I don't feel any repulsion on my finger,why?Your interest in my question will obviously benifit me.So,thankyou!
I think where you are going wrong is that you equate torque with force. That, however, is incorrect - a torque is not the same as a force. You can think of torque as the tendency of a body to rotate around an axis; the direction of the torque vector is parallel to the axis of rotation ( hence the cross product, and the vector being perpendicular to the x-y plane ), and the magnitude of the torque vector is a measure of the change in angular momentum of the rotating body. The animation on this Wikipedia page illustrates this rather well :

Torque - Wikipedia, the free encyclopedia

4. Originally Posted by Markus Hanke
Originally Posted by sagarkaran
I know well that torque is a vector product and it is a kind of work done which is parallel to the axis of rotation.But,how can torque passes through z-axis whereas it's compoment is along x and y axis?If it is true then I should feel repulsion on my finger when touch the centre tips of rotating body since torque must passes through axis.But I don't feel any repulsion on my finger,why?Your interest in my question will obviously benifit me.So,thankyou!
I think where you are going wrong is that you equate torque with force. That, however, is incorrect - a torque is not the same as a force. You can think of torque as the tendency of a body to rotate around an axis; the direction of the torque vector is parallel to the axis of rotation ( hence the cross product, and the vector being perpendicular to the x-y plane ), and the magnitude of the torque vector is a measure of the change in angular momentum of the rotating body. The animation on this Wikipedia page illustrates this rather well :Torque - Wikipedia, the free encyclopedia
Yes,you are right but my problem is not that.why torque is passses through z-axis?since component of torque are in x and y then is it right to say that torque also produces on the x,y plane.

5. Originally Posted by sagarkaran
Yes,you are right but my problem is not that.why torque is passses through z-axis?since component of torque are in x and y then is it right to say that torque also produces on the x,y plane.
It passes at right angles to the x-y plane simply because that is the axis of rotation. Look at the animation on Wikipedia - the body rotates around an axis which is perpendicular to the x-y plane, so this is how the torque vector points. You can think of "torque vector" as "axis of rotation".

6. Originally Posted by sagarkaran
Originally Posted by Markus Hanke
Originally Posted by sagarkaran
I know well that torque is a vector product and it is a kind of work done which is parallel to the axis of rotation.But,how can torque passes through z-axis whereas it's compoment is along x and y axis?If it is true then I should feel repulsion on my finger when touch the centre tips of rotating body since torque must passes through axis.But I don't feel any repulsion on my finger,why?Your interest in my question will obviously benifit me.So,thankyou!
I think where you are going wrong is that you equate torque with force. That, however, is incorrect - a torque is not the same as a force. You can think of torque as the tendency of a body to rotate around an axis; the direction of the torque vector is parallel to the axis of rotation ( hence the cross product, and the vector being perpendicular to the x-y plane ), and the magnitude of the torque vector is a measure of the change in angular momentum of the rotating body. The animation on this Wikipedia page illustrates this rather well :Torque - Wikipedia, the free encyclopedia
Yes,you are right but my problem is not that.why torque is passses through z-axis?since component of torque are in x and y then is it right to say that torque also produces on the x,y plane.
It produces components because it is a cross-product:

Do you understand how cross-product works?

7. Originally Posted by xyzt
Originally Posted by sagarkaran
Originally Posted by Markus Hanke
Originally Posted by sagarkaran
I know well that torque is a vector product and it is a kind of work done which is parallel to the axis of rotation.But,how can torque passes through z-axis whereas it's compoment is along x and y axis?If it is true then I should feel repulsion on my finger when touch the centre tips of rotating body since torque must passes through axis.But I don't feel any repulsion on my finger,why?Your interest in my question will obviously benifit me.So,thankyou!
I think where you are going wrong is that you equate torque with force. That, however, is incorrect - a torque is not the same as a force. You can think of torque as the tendency of a body to rotate around an axis; the direction of the torque vector is parallel to the axis of rotation ( hence the cross product, and the vector being perpendicular to the x-y plane ), and the magnitude of the torque vector is a measure of the change in angular momentum of the rotating body. The animation on this Wikipedia page illustrates this rather well :Torque - Wikipedia, the free encyclopedia
Yes,you are right but my problem is not that.why torque is passses through z-axis?since component of torque are in x and y then is it right to say that torque also produces on the x,y plane.
It produces components because it is a cross-product:[tex]\boldsymbol{\tau} = \mathbf{r} \times \mathbf{Do you understand how cross-product works?
Yes,I understand how cross product works.cross product is always perpendicular to the plane and is expressed as i×j.Can you explain me as non-mathematical way that how can torque passes through z-axis?Once I imagine this phenomenon I will get clearification.

8. Originally Posted by sagarkaran
,I understand how cross product works.cross product is always perpendicular to the plane and is expressed as i×j.

z-axis is perpendicular on the (x,y) plane, so, if the torque is also perpendicular on the (x,y) plane, what does this tell you?

9. Originally Posted by xyzt
Originally Posted by sagarkaran
,I understand how cross product works.cross product is always perpendicular to the plane and is expressed as i×j.
z-axis is perpendicular on the (x,y) plane, so, if the torque is also perpendicular on the (x,y) plane, what does this tell you?
It tells that the body is rotating due to which torque is produed.Is it due to torque when an axis of cyclone come into existence?

10. Originally Posted by sagarkaran
Yes,you are right but my problem is not that.why torque is passses through z-axis?since component of torque are in x and y then is it right to say that torque also produces on the x,y plane.

11. Originally Posted by xyzt
Originally Posted by sagarkaran
Yes,you are right but my problem is not that.why torque is passses through z-axis?since component of torque are in x and y then is it right to say that torque also produces on the x,y plane.