What causes rotation, a coupe or a moment?

In summary: This is because there are no other forces acting on the center of mass to counteract the applied force. In summary, a moment is a mathematical tool used to understand and calculate a couple in a real world scenario. In a special case, a couple can be resolved into 2 equal moments acting in opposite directions about a pivot. In real life, material behavior and deformation add complexity to the situation. If a force is applied to one end of a body in space with no other forces acting on the center of mass, the body will move in the direction of the applied force.
  • #1
Sarin
8
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:
 
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  • #2
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.
 

1. What is the difference between rotation and a moment?

Rotation refers to the circular movement of an object around a fixed point, while a moment is a measure of the turning effect of a force on an object.

2. What causes rotation in an object?

Rotation is caused by the application of a force on an object that is not acting directly through its center of mass. This creates a torque, or moment of force, that causes the object to rotate.

3. Can a coupe or a moment cause rotation?

Yes, both a coupe and a moment can cause rotation. A coupe is a type of force that acts perpendicular to the direction of motion, while a moment is a type of force that causes rotation. Both can create a torque that results in rotation.

4. How does the distance from the point of rotation affect the amount of rotation?

The greater the distance from the point of rotation to the point where the force is applied, the greater the amount of rotation. This is because the longer lever arm creates a larger torque, resulting in a greater rotation.

5. How can we calculate the moment of a force?

The moment of a force can be calculated by multiplying the magnitude of the force by the distance from the point of rotation to the point where the force is applied. This can be represented by the equation M = F x d, where M is the moment, F is the force, and d is the distance.

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