Where is the tension of the string coming from?

[scilearner]

Hello everyone,

 

Let's say there is a tripod. I attach a string to the tripod and then attach a mass to the string. The string with the mass ,stretches a bit and then the mass hangs in the air. So this means the weight force of the mass must be balanced by the tension of the string. Now let's say this tension is coming from the elasticity of the string. Now after the mass is hung, I take it off and look at the string, now it is stretched and loss its elasticty. So if I attach this string to the tripod again, and hang the mass, and it stretches a bit and stays stationary, where is the tension of the string coming from. It can't come from the string because it has lost its elasticity.

[J.C.MacSwell]

Hello everyone,

 

Let's say there is a tripod. I attach a string to the tripod and then attach a mass to the string. The string with the mass ,stretches a bit and then the mass hangs in the air. So this means the weight force of the mass must be balanced by the tension of the string. Now let's say this tension is coming from the elasticity of the string. Now after the mass is hung, I take it off and look at the string, now it is stretched and loss its elasticty. So if I attach this string to the tripod again, and hang the mass, and it stretches a bit and stays stationary, where is the tension of the string coming from. It can't come from the string because it has lost its elasticity.

 

So, it suffered permanent deformation from the tension of the original hanging of the mass, without full failure.

 

It still has some elasticity, "it stretches a bit and stays stationary", even if changed considerably from it's original state.

 

Some of it's properties have changed, but essentially it is loaded in substantially the same way. If it doesn't fail completely by breaking, it remains in tension.

 

The string may actually be stronger than original, the yield strength may be greater, as it may be able to carry a heavier load without further permanent deformation.

Edited May 29, 2010 by J.C.MacSwell

[Cap'n Refsmmat]

The tension in a taught string is provided by the forces on the ends of the string pulling outwards. In this case, that'd be the mass hanging, and the force the tripod applies on the string to hold it up.

[scilearner]

Hey thanks both for the replies So is the tension coming from both the tripod and the elasticity of the string? If tension is coming from the tripod, how is the tripod able to provide tension. I don't understand what causes tension. Can anyone explain in physics or molecular level what causes the tension.Now my question is simply what is the reason behind tension force. I know air resistance is caused by air but what causes tension? Also if I hang a mass to a string, and then it stretches a bit and then forces balance remains stationary. I hang a bigger mass and it stretches further and forces balance remain stationary. Why did it stretch further in the 2 nd situation for the forces to balance. Thanks

Edited May 29, 2010 by scilearner

[Severian]

Bah humbug! I thought this was going to be asking where the string tension in string theory comes from.

[ajb]

Bah humbug! I thought this was going to be asking where the string tension in string theory comes from.

 

That was also my initial thought!

 

I am not sure how I would answer that. It is analogous to the mass or energy of a point particle.

[Physicsfan]

How about this explanation?

 

the Young Modulus of the string [imath]Y=\frac{Stress}{Strain}[/imath]

so more the deformation of the string, more is the stress, in the opposite direction to that of the weight of the mass. So the string would undergo deformation until the stress and the weight are equalized.

Edited June 2, 2010 by Physicsfan
Consecutive posts merged.