Are work and moment the same thing? They both have the same units

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SUMMARY

Moment and work are distinct physical concepts, despite sharing the same dimensional units of Newtons-meters (Nm). Work is defined as the product of force and distance in the same direction, while moment (or torque) involves force applied perpendicularly to the distance (lever arm). Therefore, if an object does not move, the work done is zero, even if a moment is applied. Understanding these differences is crucial for accurate calculations in physics.

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  • Understanding of Newton's laws of motion
  • Familiarity with vector operations (dot product and cross product)
  • Basic knowledge of units of measurement in physics
  • Concept of torque and its application in mechanics
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Students of physics, engineers, and anyone interested in understanding the fundamental differences between work and moment in mechanical contexts.

Femme_physics
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Moment is Newtons per meter, and work is Newtons per meter. I'm confused as to how to relate them. Are they essentially the same thing?
 
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Femme_physics said:
Moment is Newtons per meter, and work is Newtons per meter. I'm confused as to how to relate them. Are they essentially the same thing?

Correction : Moment is Newtons-meters, and work is Newtons-meters.

No they're not the same. For work the force has to be in the same direction (vector dot product) as relevant distance (that is the distance traveled), whereas for torque the force has to be perpendicular (vector cross product) to the relevant distance (which is the lever length).
 
Ah I see, thanks uart :)
 
I just thought of something.

If I push on something with 400 NEwtons, and it doesn't move - does work = 0? Or 400 N/m?

Because if I apply a moment on something and it doesn't rotate, I know that the moment is still worth its amount regardless of whether there was or wasn't rotational movement.
 
Work is force x distance. So there is no work done if the object doesn't move.

N/m is a unit of pressure. Work units is Nm.
 
Ah, sorry for repeatedly confusing the units...and thanks for clarifying my suspicion, jarednjames.
 
jarednjames said:
N/m is a unit of pressure. .

Huh? Not N/m^2?
 
Oldfart said:
Huh? Not N/m^2?

Bugger, good catch!
 
Dimensionally, torque (moment) has the same units as energy. However, that alone does not give you permission to add these totally different quantities.
 

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