Will Block M2 Move Left? Understanding Forces in a Connected Spring System"

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    Block Spring compression
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Discussion Overview

The discussion revolves around the dynamics of two blocks, m1 and m2, connected by a spring on a frictionless surface, particularly focusing on the effects of an external force applied to block m1. Participants explore the implications of this setup on the motion of block m2 and the forces involved in the spring system.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions whether block m2 will move to the left when an external force is applied to block m1, citing the spring's force generation in the opposite direction of its displacement.
  • Another participant introduces a hypothetical scenario where the mass of block m2 is zero, prompting a discussion on the implications for the force on block m1 and the application of Newton's 3rd law.
  • Some participants assert that if m2 has zero mass, block m1 would simply accelerate according to the applied force divided by its mass, questioning the relevance of the original inquiry.
  • There is a discussion about the necessity of a counterforce acting on m2 for block m1 to experience a leftward force, emphasizing the role of the spring's displacement.
  • One participant highlights the ambiguity in the teacher's question, suggesting that different interpretations could lead to varying conclusions about the system's behavior.
  • Another reiterates the principle that a spring exerts forces in opposite directions when compressed or stretched, reinforcing the idea that both ends of the spring experience forces.

Areas of Agreement / Disagreement

Participants express differing views on the implications of the spring's behavior and the effects of an external force on the blocks. There is no consensus on whether block m2 will move left or how the system behaves under the condition of m2 having zero mass.

Contextual Notes

The discussion is limited by assumptions regarding the mass of block m2 and the initial conditions of the spring. The interpretations of the forces acting on the blocks and the spring's behavior are not fully resolved.

navneet9431
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Suppose two blocks m1 and m2,connected by a spring are kept on a frictionless surface and the block m1 is applied an external force F.
My teacher taught me that in a spring the force is generated in the direction opposite to the displacement of the spring.
So the spring would generate a force in the left direction as it's displacement would be right.
So my question is that will the block m2 move in the *left* direction or not as a force is getting applied on it in the left direction?
I will be thankful for help!
 

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What would happen, if the mass of block ##m_2## would be zero? What would be the force on ##m_1##? Try to apply Newton's 3rd law.
 
If mass of m2 is zero then block m1 would just move with acceleration F/m1.
What are you trying to explain?
stockzahn said:
What would happen, if the mass of block ##m_2## would be zero? What would be the force on ##m_1##? Try to apply Newton's 3rd law.
 
navneet9431 said:
If mass of m2 is zero then block m1 would just move with acceleration F/m1.
What are you trying to explain?

There only would be a force to the left acting on ##m_1## if there is a "counterforce" acting to the right on ##m_2##. From the perspective of ##m_2## the displacement of the spring would be to the left.
 
navneet9431 said:
My teacher taught me that in a spring the force is generated in the direction opposite to the displacement of the spring.
Have you never compressed/stretched a spring with your hands? It should be obvious that it applies two opposite forces at both ends.
 
The teacher's question is not tightly enough specified for a rigorous answer. This is not as harmless a fault as you might think because two different people could interpret it in two different ways.
If we assume that the spring is at its equilibrium length then what would cause any movement to the left if the input force F is to the right?
What do we know about the forces at each end of a light spring or a light string?
 
navneet9431 said:
My teacher taught me that in a spring the force is generated in the direction opposite to the displacement of the spring.
The spring resists being compressed or being stretched. Here, the spring is compressed and it will exert an outward force at each end.
 

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