Force and acceleration in object at rest

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Homework Help Overview

The discussion revolves around the dynamics of an object at rest that is subjected to an increasing pulling force via a rope. The central question pertains to the relationship between the applied force and the resulting acceleration of the object, particularly in the context of frictional forces.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to reconcile the concept of acceleration being zero for an object at rest with the idea of an increasing pulling force. They express confusion regarding the implications of force on acceleration.
  • Some participants clarify the role of friction, noting that the net force must be considered to determine acceleration, which leads to further exploration of the relationship between applied force and friction.

Discussion Status

The discussion is progressing with participants providing clarifications regarding the distinction between applied force and net force. There is acknowledgment of the original poster's confusion, and a correct understanding of the forces involved is being developed.

Contextual Notes

Participants are considering the effects of friction and the conditions under which the object will begin to accelerate, highlighting the importance of net force in this scenario.

blueberryfive
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Homework Statement



An object is at rest and stays at rest, but a rope attached to it is pulling with increasing force. What is the acceleration?

Homework Equations



F=ma

The Attempt at a Solution



The solution is that acceleration is constant and 0. Obviously a= dv/dt =0, since the object is at rest.

But if force is increasing, since F=ma, isn't acceleration increasing as well?

This is probably a stupid question, but I'm confused
 
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Consider a block of wood on a table. As you gradually start pulling, or pushing, on the block, the force will obviously increase but the friction force will be equal to and opposite the force you are applying up to a maximum value. When the friction force is exceeded, then the block will accelerate according to F = ma where F is the net force on the block. The net force will be the force you are pulling with minus the friction force. Then there will be acceleration.
 
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Thanks, so I guess my problem is that F is the net force, not just the pulling force applied to the block.
 
That is correct.
 

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