Question about Tension 100 identical blocks

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Homework Help Overview

The problem involves 100 identical blocks on a frictionless surface, connected by massless strings, with a force of 100 N applied to the first block. Participants are tasked with finding the tension in specific strings connecting adjacent blocks.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to apply Newton's second law to find tensions in the strings but expresses confusion about their calculations. Some participants suggest treating the blocks as a single mass to simplify the problem and consider the uniform acceleration of all blocks.

Discussion Status

Participants are exploring different interpretations of the problem, with some providing guidance on how to approach the calculation of tension. There is an ongoing discussion about the implications of adding friction to the scenario, indicating that multiple perspectives are being considered.

Contextual Notes

The original poster is uncertain about the correct application of equations and assumptions regarding the system's behavior, particularly in relation to tension and friction. The discussion includes hypothetical scenarios that introduce additional variables.

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Each of 100 identical blocks sitting in a frictionless surface is connected to the next block by a massless string. The first block is pulled with a force 100 N.

a) what is the tension in the string connecting block 100 to block 99

B) what is the tension in the string connecting block 50 to 51?

I don't know how to do this. The only equation I got was T2-T1=ma for box 99 where T2 is the tension string attaching to box 98 and T1 is the tension in the string attached to 100. Also for box 100 I got -T=ma and plugged this into the equation -100 + T=ma and got T=50 N but this is wrong for part A and is supposed
To be the answer for part B but I don't see why. Can you please explain how to do this?
 
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Assuming the string doesn't stretch, all the masses will have the same acceleration. So, think of the entire set of blocks as a single mass being pulled and solve for the acceleration. Then you can determine the string tension between any of the blocks by considering all blocks upstream to be a single mass and all blocks downstream to be a single mass, thereby having a two block system.
 
Does this picture make it any easier? All the blocks accelerate the same but you can combine blocks.

blocks.JPG



oops, edit, someone answered whilst I was drawing.
 
So if there were a coefficient of friction of say 0.1 in this problem, then the 99 blocks together would produce a friction force of 0.1 x 99M x g and the one block to the right would produce a friction force of 0.1 x M x g.
And each of these two friction forces would be the amount that is added to its corresponding equation. Right?
 

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