Tension in a String: Explained

In summary, the direction of tension in a string is upward on both masses. The acceleration constraint dictates that the acceleration of one mass will be equal and opposite to the other. The choice of coordinate system and signs in the equations is arbitrary, as long as they are consistent and follow the convention of up being + and down being -. It may be helpful to draw a free body diagram and split the system into parts for better understanding.
  • #1
Aladin
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Please explain the direction of tension in a string .
 

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  • #2
please repply me as soon as possible
 
  • #3
What is your coordinate system? Where is your origin, which direction is positive and which direction is negative?
 
  • #4
Recall that at any point on a string under tension, there will be a force acting up and another force acting down the string. Furthermore, recall that these forces must be equal.
 
  • #5
acceleration constraint

Aladin said:
Please explain the direction of tension in a string .
I suspect that you understand perfectly well that the string tension pulls up on both masses. What you are trying to understand is how the signs are chosen in the equations.

What you need to understand is the how the acceleration of m_1 relates to the acceleration of m_2. Since they are connected by a cord, they are constrained to move together. If you arbitrarily call the acceleration of m_1 to be "a" upward, what must be the acceleration of m_2?

Once you understand the above "acceleration constraint", you can pick a coordinate system and write your equations. For example, choose up to be + and down to be -. Use that convention and try writing the equations for each mass.
 
  • #6
Doc Al said:
Once you understand the above "acceleration constraint", you can pick a coordinate system and write your equations. For example, choose up to be + and down to be -. Use that convention and try writing the equations for each mass.

Right. And if all else fails, split your system into parts and draw your FDB with your axes included.
 
  • #7
I am not understand please just tell me about the sign that are used in both equations.
 

Related to Tension in a String: Explained

What is tension in a string?

Tension in a string is the force applied to the string that causes it to stretch or resist being pulled apart.

What are the factors that affect the tension in a string?

The tension in a string is affected by the force applied to it, the length of the string, and the thickness or stiffness of the string.

How is tension in a string measured?

Tension in a string is measured in units of force, such as pounds or newtons, using a device called a tensiometer or tension gauge.

What is the relationship between tension and frequency in a string?

The tension in a string is directly proportional to the frequency of the sound produced when the string is plucked or struck.

How does tension affect the speed of a wave in a string?

The higher the tension in a string, the faster the speed of the wave traveling through the string. This is due to the increased stiffness of the string at higher tensions.

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