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Blocks being pulled by a string

by alexialight
Tags: blocks, pulled, string
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Mar23-05, 06:47 AM
P: 7
I'm just starting to get my head around the concepts of Tension and Force but I'm stuck on this question, I was wondering if anyone could help me out?

Q: 3 identical blocks connected by ideal strings are being pulled along a horizontal frictionless surface by a horizontal force F. The magnitude of the tension in the string between blocks B and C is T. Assume that each block has mass m.

i> What is the magnitude of the force? (Expressed in terms of T)
ii> What is the magnitude of the accleration of the three blocks (in terms of m and F)?

I worked out the acceleration on block B (T/(2*m)) but don't know what to do next. I'd really appreciate any help with this.
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Mar23-05, 06:51 AM
P: 20
The acceleration is the same for the entire system. So the force must be (m1 + m2 + m3)*a

hope that helps
Mar23-05, 06:58 AM
P: 7
I think it does... that would make the Force 3/2*T right?
So in terms of m and F, the acceleration would be F/3m ?

Mar23-05, 07:35 AM
P: 453
Blocks being pulled by a string

Yes, you are right.

[tex]F - T = m_ca[/tex],


[tex]F = T + m_ca = T + m(\frac{T}{2m}) = \frac{3}{2}T[/tex]
Mar23-05, 08:00 AM
P: 7
Awesome - Thanks a lot

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