What causes rotation, a coupe or a moment?

  • Thread starter Thread starter Sarin
  • Start date Start date
  • Tags Tags
    Moment Rotation
AI Thread Summary
The discussion centers on the physical significance of moments and couples in causing rotation. It questions whether moments are merely theoretical constructs or if they have tangible effects in real-world scenarios. A couple, defined as two equal moments acting in opposite directions, is highlighted as a specific case of a moment. The conversation also explores the behavior of an extended bar or rod in space when a force is applied to one end, concluding that it would move in the direction of the applied force. Overall, the complexities of material behavior and deformation in practical applications are acknowledged.
Sarin
Messages
8
Reaction score
0
Does a moment have any real (physical) significance or is it just a definition/ an aid to understand and calculate a couple. Is it that the rotation is actually caused by a couple!

I know we can resolve a force causing a moment about a point into a couple and an equal force acting at that point, but what i want to know is how does this actually happen in a real world scenario.

Also,
Say if there was a body (an extended bar or rod) in space so that no force would act on its centre of mass, then if a force F was applied on one of its ends what would happen and why?

forgive me if the question sounds stupid, but this concept has ben bugging me for a very long time now!:confused:
 
Engineering news on Phys.org
Sarin said:
Does a moment have any real (physical) significance or is it just a definition/ an aid to understand and calculate a couple. Is it that the rotation is actually caused by a couple!

A couple is a special case of a moment when 2 equal moments act in opposite direction about a pivot.

I know we can resolve a force causing a moment about a point into a couple and an equal force acting at that point, but what i want to know is how does this actually happen in a real world scenario.

The resolving of forces is (in my opinion anyway) a useful mathematical tool but in real life such things as the material constituent behaviour come into play and things get much more complicated, especially if the material deforms.

Say if there was a body (an extended bar or rod) in space so that no force would act on its centre of mass, then if a force F was applied on one of its ends what would happen and why?

It would move in the direction of the applied force.
 

Thread 'Race car suspension Class'

Posted June 2024 - 15 years after starting this class. I have learned a whole lot. To get to the short course on making your stock car, late model, hobby stock E-mod handle, look at the index below. Read all posts on Roll Center, Jacking effect and Why does car drive straight to the wall when I gas it? Also read You really have two race cars. This will cover 90% of problems you have. Simply put, the car pushes going in and is loose coming out. You do not have enuff downforce on the right...
View full post »
Thread 'Physics of Stretch: What pressure does a band apply on a cylinder?'

Thread 'Physics of Stretch: What pressure does a band apply on a cylinder?'

Scenario 1 (figure 1) A continuous loop of elastic material is stretched around two metal bars. The top bar is attached to a load cell that reads force. The lower bar can be moved downwards to stretch the elastic material. The lower bar is moved downwards until the two bars are 1190mm apart, stretching the elastic material. The bars are 5mm thick, so the total internal loop length is 1200mm (1190mm + 5mm + 5mm). At this level of stretch, the load cell reads 45N tensile force. Key numbers...
View full post »

Thread 'Cantilever help'

I'm trying to decide what size and type of galvanized steel I need for 2 cantilever extensions. The cantilever is 5 ft. The space between the two cantilever arms is a 17 ft Gap the center 7 ft of the 17 ft Gap we'll need to Bear approximately 17,000 lb spread evenly from the front of the cantilever to the back of the cantilever over 5 ft. I will put support beams across these cantilever arms to support the load evenly
View full post »

Similar threads

Understanding Couples, Moments & Forces
Replies
8
Views
2K
3D Equillibrium Statics Problem - Reaction Forces/Moments
Replies
4
Views
2K
I Moment of Inertia about an axis and Torque about a point
Replies
5
Views
3K
I What Causes the Einstein - de Haas Effect in Iron Rods?
Replies
39
Views
5K
What's the most likely cause for this carbon seal crack?
Replies
8
Views
143
What causes rotation, a couple or a moment? (conceptual)
Replies
5
Views
4K
Calculating bend moment of a rotating cutting tool....?
Replies
1
Views
3K
Torque required to rotate an object at an angle
Replies
1
Views
2K
What Is the Instantaneous Center of Rotation and How Is It Chosen?
Replies
19
Views
3K
Extending an aircraft landing gear that has gotten stuck
Replies
18
Views
3K

Hot Threads

Recent Insights

Back
Top