How Does Tension in the String Compare to the Force on Block A?

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Homework Help Overview

The discussion revolves around the forces acting on two blocks, A and B, connected by a massless string on a frictionless surface. The original poster questions the relationship between the tension in the string and the force applied to block A by a hand.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants explore the forces acting on block A, considering the tension in the string and the applied force. There are discussions about the implications of the blocks moving with the same acceleration and the conservation of tension in the string.

Discussion Status

The discussion includes various interpretations of the forces involved, with some participants suggesting that the applied force on block A must be greater than the tension in the string. There is an acknowledgment of the tension being consistent throughout the string, but no explicit consensus has been reached.

Contextual Notes

Participants are working under the assumption that the surface is frictionless and that the string is massless, which may influence their reasoning about the forces and tensions involved.

Jimmy1234
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Homework Statement


The hand in the figure is pushing on the back of block A. Blocks A and B, with mass B > mass A, are connected by a massless string and slide on a frictionless surface.

Is the force of the string on B larger than, smaller than, or equal to the force of the hand on A?

Picture: http://img713.imageshack.us/img713/1030/physicsq.jpg

Homework Equations


The Attempt at a Solution



From my free body diagram, block B has a tension towards the right that should be less than the force applied to block A as they both move with the same acceleration.
 
Last edited by a moderator:
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Consider the forces on block A.
 
Block A has a force to the right and tension in the opposing direction. Because of conservation of string, the tension should be the same for Block B? Since this is on a frictionless surface, nothing is opposing the force applied on A so there will be an acceleration to the right meaning tension should be less than the force?
 
I'd state it this way: The only forces on block A are the applied force and the string tension. The the blocks accelerate, so there must be a net force on A, thus the applied force must be greater than the tension. (And the tension is the same throughout a massless rope.)
 
Thank you! This thread can be closed.
 

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