Infinite acceleration on a string?

In summary: It could mean that the string is inextensible (unbreakable and maximally stretched) or that the force is infinite in the limit (if the mass of the string is negligible).
  • #1
PhysicsKid0123
95
1
I'm trying to figure out what it says in my book. Here is the link of the picture. http://i941.photobucket.com/albums/...oads/7D0D3CE4-A11E-4F0F-A2A5-836D03945AE5.jpg Could someone explain the part where it says "Otherwise, there would be a net tension force acting on the sections, and they would consequently suffer an infinite acceleration." Why does it necessarily have to be infinite? The only reason why I see it should be infinite is if the string is inextensible (unbreakable and maximally stretched) and if it so happened to not be straight it must have some infinite force so to not make it straight. Is my logic correct?http://[URL=http://s941.photobucket.com/user/markangela/media/Mobile%20Uploads/7D0D3CE4-A11E-4F0F-A2A5-836D03945AE5.jpg.html][PLAIN]http://i941.photobucket.com/albums/ad259/markangela/Mobile%20Uploads/7D0D3CE4-A11E-4F0F-A2A5-836D03945AE5.jpg
 
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  • #2
The mass of the string is assumed to be negligible. If you put that into F=ma, a finite force leads to an extremely large ("infinite" in the limit) acceleration.
 
  • #3
mfb said:
The mass of the string is assumed to be negligible. If you put that into F=ma, a finite force leads to an extremely large ("infinite" in the limit) acceleration.

What do you mean exactly by "put that into F=ma." You are saying that if there were to be some sort of force or tension then a approaches "infinity" as m approaches "zero" in some sense?
 
  • #4
If tension would be different in different parts of the string, then there would be a force acting on a section of string.

A force acting on an object with a very small mass will lead to a very large acceleration (as F=m*a).
A force acting on an object with a very very small mass will lead to a very very large acceleration.
A force acting on an object with zero mass will lead to an "infinite" acceleration. (note the " ", because this does not exist in reality).
 
  • #5
mfb said:
If tension would be different in different parts of the string, then there would be a force acting on a section of string.

A force acting on an object with a very small mass will lead to a very large acceleration (as F=m*a).
A force acting on an object with a very very small mass will lead to a very very large acceleration.
A force acting on an object with zero mass will lead to an "infinite" acceleration. (note the " ", because this does not exist in reality).
Okay I think I see now. So the author's use of infinite accel. is ambiguous.
 

Related to Infinite acceleration on a string?

1. What is infinite acceleration on a string?

Infinite acceleration on a string refers to an idealized scenario where a mass attached to a string experiences an instantaneous increase in acceleration without any external forces acting on it.

2. Is infinite acceleration on a string possible in reality?

No, infinite acceleration on a string is a theoretical concept and cannot be achieved in reality. In the real world, there will always be external forces acting on the mass, such as air resistance or friction, which will limit its acceleration.

3. What is the significance of infinite acceleration on a string?

Infinite acceleration on a string is used as a simplifying assumption in theoretical physics to understand the behavior of systems with rapid changes in acceleration. It helps in developing mathematical models and making predictions about the motion of objects.

4. Can infinite acceleration on a string violate the laws of physics?

No, infinite acceleration on a string is a concept that is consistent with the laws of physics. It does not violate any fundamental principles but is used as an idealized scenario to understand complex systems.

5. How is infinite acceleration on a string related to the concept of infinite velocity?

Infinite acceleration on a string does not necessarily lead to infinite velocity. In reality, when an object experiences infinite acceleration, it will eventually reach a maximum velocity due to external forces. The concept of infinite velocity is not possible in our physical world.

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