Perpendicular force calculated from torque and point of application?

In summary, Miki is trying to find the force that causes torque on a body consisting of mass-points in ℝ^{3}. They have found the equation \tau = r\timesF, but are struggling to calculate F_{\bot}. They suggest calculating an arbitrary F and subtracting the component of F_{||} to find F_{\bot}. They also mention that the given \tau and r are not perfectly perpendicular, but believe their method is correct. They thank the person for their help.
  • #1
Mikipedia
3
0
I hope I managed to post my question the right place!

I have a body consisting of a bunch of mass-points in ℝ[itex]^{3}[/itex], and when torque is applied to this body, I'm interested in finding the force that must have caused the torque based on the point of application and the torque vector, which are given.

I see the form;
[itex]\tau[/itex] = r[itex]\times[/itex]F
quite often, such as it is seen in wikipedia (which offers a nice overview btw).

I understand that it is not possible to calculate F, but I find it hard to believe that F[itex]_{\bot}[/itex] is impossible to calculate since it should be unique, yet I don't see such an equation anywhere. Any pointers would be greatly appreciated!

Cheers,
Miki
 
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  • #2


Calculate an arbitrary F which satisfies the equation, subtract the component of ##F_{||}##.
 
  • #3


I see, clever :)

May this arbitrary F (how about we call it F'?) be obtained by;
F' = r×[itex]\tau[/itex]/r[itex]\bullet[/itex]r ?

I'm feeding the result I get back into the form
[itex]\tau[/itex] = r×F
and as I've realized, the [itex]\tau[/itex] and r I am given are not perfectly perpendicular so my [itex]\tau[/itex]' is similar to [itex]\tau[/itex] at best. But that method seems like it would be correct!

Thank you very much!
Miki
 
Last edited:

1. What is a perpendicular force?

A perpendicular force is a force that acts at a right angle to a surface or object. It is also known as a normal force.

2. How is torque related to perpendicular force?

Torque is a measure of the force that causes an object to rotate around a pivot point. Perpendicular force is one component of this force and is calculated by multiplying the magnitude of the force by the distance from the pivot point.

3. How do you calculate the perpendicular force from torque?

The perpendicular force can be calculated by dividing the torque by the distance from the pivot point.

4. What is the point of application in this context?

The point of application refers to the location where the perpendicular force is applied. This can be at any point along the object's surface, but it must be at a right angle to the surface.

5. Can perpendicular force be negative?

Yes, perpendicular force can be negative if the direction of the force is opposite to the direction of rotation. This can happen if the force is applied at a point closer to the pivot point than the distance being measured.

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