Solving for Acceleration & Tension in Two Mass System

AI Thread Summary
The discussion focuses on a physics problem involving two masses on a frictionless surface connected by a string and a third mass hanging vertically. The goal is to determine the system's acceleration and the tensions in the horizontal strings. The provided equations for acceleration and the initial calculation yield an acceleration of 2.3 m/s². Participants emphasize the need for three free-body diagrams (FBD) to analyze the forces acting on each mass, including tension and weight. Clarification is sought regarding the attachment of the masses to the string, indicating a need for precise understanding of the system's configuration.
Izzybee
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Homework Statement


Two masses, located on a frictionless, horizontal surface, are tied together by a string. The masses are attached to a second string which passes over a pulley and has a third weight attached which hangs vertically. Find the acceleration of the system and the tensions of the horizontal strings. (uk: .15) Mass 1= 10 kg attached to Mass 2: 20kg attached to mass 3 (vertical): 15kg.


Homework Equations



F=ma
a= (m2-ukm1)g/ (m1+m2)
a= (m2-m1)g/ (m1+m2)

The Attempt at a Solution



a= (15-.15*30)9.8/ 45
a= 2.3 m/s2

Please help ASAP!
 
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what do your force-body diagrams look like?

also, you need 3 FBD since you're dealing with 3 masses.
 
Hi! It's in the attachment.

Thanks,
 

Attachments

your attachment will take too long to be approved, you're better off just linking it
 
I don't really know how to do that! But the vertical one is with tension going up and weight going down, the first weight is normal force going up and weight going down, and the second horizontal weight is normal force going up and weight going down. The tensions are up for the vertical weight and to the left for the two horizontal weights.
 
Izzybee said:
I don't really know how to do that! But the vertical one is with tension going up and weight going down, the first weight is normal force going up and weight going down, and the second horizontal weight is normal force going up and weight going down. The tensions are up for the vertical weight and to the left for the two horizontal weights.
is this what your FBD should look like?

http://img89.imageshack.us/img89/5333/probnj2.jpg

are they both attached to the string or just the lower box?
 
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