Can Torque Be Applied to an Object Through Linear Forces Alone?

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The discussion centers on the application of torque and moments in physics, specifically questioning why a moment isn't calculated as a force multiplied by distance. It clarifies that an applied moment is already defined by its magnitude and direction, and does not require further multiplication by distance. The conversation highlights that torque can be conceptualized as the result of two equal and opposite forces acting along parallel lines. While the theoretical application of moments is acknowledged, the participants note that in practical scenarios, torque is typically generated through linear forces. Ultimately, the discussion emphasizes the distinction between applied moments and the forces that create them.
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Homework Statement


Why the moment isn't=15* 3Nm? Since we are taking moment about point O...it's 3m away from O

Homework Equations

The Attempt at a Solution

 

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goldfish9776 said:

Homework Statement


Why the moment isn't=15* 3Nm? Since we are taking moment about point O...it's 3m away from O

Homework Equations

The Attempt at a Solution

Are you referring to the 15kNm moment that is applied? You don't multiply that by a distance. (It would give you something with units kNm2.) a force times a perpendicular distance gives a moment, but an applied moment is already a moment. Exactly where it is applied makes no difference, only its magnitude and direction matter.
 
haruspex said:
Are you referring to the 15kNm moment that is applied? You don't multiply that by a distance. (It would give you something with units kNm2.) a force times a perpendicular distance gives a moment, but an applied moment is already a moment. Exactly where it is applied makes no difference, only its magnitude and direction matter.
ya , i knew that . But , how can be moment be applied? only force can be applied , right?
 
goldfish9776 said:
ya , i knew that . But , how can be moment be applied? only force can be applied , right?
Are you asking as a practical matter how it is possible to apply a moment as opposed to a force? There does not need to be a way to do that. Consider turning a nut using a spanner. One can think of it as applying a torque, or as applying two equal and opposite forces along parallel but different lines of action. If you are told a moment of some specified magnitude and direction is applied, you do not need to care about how it is applied.
 
haruspex said:
Are you asking as a practical matter how it is possible to apply a moment as opposed to a force? There does not need to be a way to do that. Consider turning a nut using a spanner. One can think of it as applying a torque, or as applying two equal and opposite forces along parallel but different lines of action. If you are told a moment of some specified magnitude and direction is applied, you do not need to care about how it is applied.
yes, this will only occur in the exercise , but not in daily life ?
 
goldfish9776 said:
yes, this will only occur in the exercise , but not in daily life ?
I cannot think of a way to apply a torque to an object (in an inertial frame) other than by a combination of linear forces.
 

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