Moments - How are they actually calculated?

[012anonymousx]

Moments -- How are they actually calculated?

Hello, I have a question.

Is the moment calculated:

Force times the distance or

Force's perpendicular component (to axis) times the distance.

For example, let's say I have a stick.

Pulling on it is not moment.

So if I push at the stick to an angle, the way I calculate the force that the other side is applying is by taking the perpendicular component of my Fa and multiplying it by the distance.

Is that correct?

 

[rock.freak667]

Yes, when you are calculating moments, you would use the perpendicular component. The parallel component will not produce any moment as the perpendicular distance is zero.

 

[jhae2.718]

Mathematically, a moment is $\vec{l} = \vec{r} \times \vec{f}$. The magnitude comes out as $l = rf\sin\theta$, where $\theta$ is the angle between the position vector and the force vector. This is equivalent to saying that it is the perpendicular component of the force.

 

[012anonymousx]

Thank you!

 

[PJC01]

Thank you for your question. The calculation of moments depends on the specific situation and the type of moment being calculated. Generally, moments are calculated by multiplying a force by the distance from the point of rotation to the line of action of the force. This can be done using either the perpendicular component of the force or the full force vector, depending on the angle at which the force is applied. In your example with the stick, if you are applying a force perpendicular to the stick, then yes, you would use the perpendicular component of the force in your calculation. However, if you are applying the force at an angle, you would need to use the full force vector in your calculation. I hope this helps clarify the concept of moments for you.