How is the tension equal in both sides of the string

In summary: The force on the pulley will be less than the sum of the weights because the CM of the two masses is accelerating downwards.In summary, the tension in both sides of the string is equal when it is over a pulley with two different masses attached. This is based on the assumption that the pulley is massless and frictionless, resulting in an equal distribution of forces on both sides of the string. The force on the pulley will be less than the sum of the weights due to the acceleration of the center of mass of the two masses.
  • #1
Miraj Kayastha
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How is the tension equal in both sides of the string, if the string is over a pulley with two different masses attached to its sides?
 
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  • #2
The smaller mass accelerates up, which requires more force than the just the weight. On the other side its the opposite.
 
  • #3
Can you explain what you mean by "On the other side its the opposite."
 
  • #4
The greater mass accelerates down, which requires less force in the rope than the weight.
 
  • #5
Miraj Kayastha said:
How is the tension equal in both sides of the string, if the string is over a pulley with two different masses attached to its sides?

The same force acts on both masses but they are not in equilibrium so there is acceleration. If the pulley is massless and frictionless, there can be no extra force on one side or the other of the string length - so the forces must be equal. The force on the pulley will be less than the sum of the weights because the CM of the two masses is accelerating downwards.
 
  • #6
I did not get you, can you explain in a different way please
 
  • #7
How's this?
If there were two rockets, pulling at either end of a string then would not the tension be the same in either direction and all along the ideal string? (That's the basis for all the Mechanics we ever use.)
Merely putting a pulley in the way and re-directing the forces, there is nothing to change that. The force on the pulley will be twice the tension because the pulley is not accelerating and must be in equilibrium.
 
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Likes yucheng
  • #8
i want to know whether it is an assumption or not
 
  • #9
sumanprakasam said:
i want to know whether it is an assumption or not
The assumption is:
sophiecentaur said:
If the pulley is massless and frictionless, there can be no extra force on one side or the other of the string length - so the forces must be equal.
 

1. What is tension in a string?

Tension is the force applied to a string that causes it to stretch or be pulled taut. It is measured in units of force, such as newtons or pounds.

2. Why is tension equal in both sides of a string?

According to Newton's Third Law of Motion, for every action, there is an equal and opposite reaction. This means that the force applied to one end of a string will be exerted back on the other end, resulting in equal tension on both sides.

3. How does tension affect a string's behavior?

The amount of tension in a string determines how it will behave. Higher tension will result in a string that is stiffer and produces higher-pitched sounds, while lower tension will make the string more flexible and produce lower-pitched sounds.

4. Is tension always equal in both sides of a string?

In most cases, yes. However, there are some factors that can affect tension, such as the elasticity and thickness of the string, as well as external forces acting on the string. These can cause slight variations in tension on each side of the string.

5. How can tension be adjusted in a string?

Tension can be adjusted by changing the force applied to the string or by altering the length or thickness of the string. For example, tightening the tuning pegs on a guitar will increase the tension in the strings, resulting in higher-pitched sounds.

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