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Applying Newton's Laws and solving multiple object system question!

  • Thread starter Allen93
  • Start date
  • #1
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Homework Statement


A 3.00-KG mass and a 10.0-KG mass are attached to opposite ends of a massless cord which is strung over a frictinoless pulley.
a) What is the acceleration of the two-mass system?
b) What is the tension in the cord?


Homework Equations



F = net forces
Fg = force due to gravity
a = acceleration
m = mass
* = times (multiply)
g = gravity

Fg = m*g
F = ma


The Attempt at a Solution


I tried to draw a free body diagram of the two objects as one system, subtracting the least massive object from the most massive object (10 kg minus 3 kg). I then found the Fg of the system and used it to find the acceleration, then found the tension force using the acceleration found. According to the answer key, I am off, could anyone please show me the light?
 

Answers and Replies

  • #2
631
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Once you draw the free body diagram, write down force equation (net force = mass*acceleration) for each of the bodies, separately. Then you can solve for acceleration.
 
  • #3
1,137
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Welcome to PF

please can you post your FBD's?

just a rough drawing will work
 
Last edited:
  • #5
1,137
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i know what is atwood machine and i understood he ques.

i just want to make sure that is FBD's are right
 
  • #6
631
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Ahh I'm sorry, I thought it's the OP asking for FBD. :zzz:
 
  • #7
12
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Welcome to PF

please can you post your FBD's?

just a rough drawing will work
I apologize for replying so late but here's the FBD.
 

Attachments

  • #8
12
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Once you draw the free body diagram, write down force equation (net force = mass*acceleration) for each of the bodies, separately. Then you can solve for acceleration.
Thank you!
I reworked the problem and set it up your way and I found the correct solution.
Thank you guys, it was really helpful.
 

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