Series of masses and pulleys

  • Thread starter Amir80om
  • Start date
  • #1
1
0

Homework Statement


Sorry for bad english[/B]
There is serie of mass and pulleys. We Know we have more than two masses. System is balanced.We take m(m<<1) from on of the masses and add to another one.
a) prove all the masses except these two have downward accleration
b) prove mass with heavier has accleration downward and mass with lighter has accleration upward
c) prove that all acclerations are relevant to m^2

Homework Equations




The Attempt at a Solution


a) First System is balanced and when we take m out of one mass there will be accleration => speed of center of mass will increase => potential energy of center of mass will reduce => center of mass has downward accleration => T is Force that connects pulleys to wall and M is sum of all masses T<MG I dont Know how to prove this for all the masses individually.
b) since all the mass except two masses have downward acclerations and length of rope is constant one of two masses or both of them must have acclerations upward. Heavier mass is going down relevant to lighter mass but I dont know how to prove (b)
 
Last edited:

Answers and Replies

  • #2
haruspex
Science Advisor
Homework Helper
Insights Author
Gold Member
38,009
7,706
Can we assume that a single string runs through the system? If so, consider what happens to its tension and how that affects the balance on each of the unchanged masses.
 
  • #3
21,950
4,996

Homework Statement


Sorry for bad english[/B]
There is serie of mass and pulleys. We Know we have more than two masses. System is balanced.We take m(m<<1) from on of the masses and add to another one.
a) prove all the masses except these two have downward accleration
b) prove mass with heavier has accleration downward and mass with lighter has accleration upward
c) prove that all acclerations are relevant to m^2

Homework Equations




The Attempt at a Solution


a) First System is balanced and when we take m out of one mass there will be accleration => speed of center of mass will increase => potential energy of center of mass will reduce => center of mass has downward accleration => T is Force that connects pulleys to wall and M is sum of all masses T<MG I dont Know how to prove this for all the masses individually.
b) since all the mass except two masses have downward acclerations and length of rope is constant one of two masses or both of them must have acclerations upward. Heavier mass is going down relevant to lighter mass but I dont know how to prove (b)
Is there a diagram of this thing, or are we supposed to have ESP?
 
  • #4
56
5
It would be useful if you could upload a diagram or a sketch of the system, as it is difficult to visualize the masses that should be hanging.

PD: If your native language is Spanish or French I could post the answer with it.
 
  • #5
haruspex
Science Advisor
Homework Helper
Insights Author
Gold Member
38,009
7,706
Is there a diagram of this thing, or are we supposed to have ESP?
My impression is that there is no specific set-up. One is supposed to demonstrate these as general results.
I think I see how to do it if we can assume that it is a single string running through the system.
 
  • #7
56
5
Please do not. This is a homework forum. Read the guidelines.

I mean I could offer the tips and/or explanations required in the native language of the OP so it's easier for them to read. I don't see how that is against the guidelines.
 
  • #8
haruspex
Science Advisor
Homework Helper
Insights Author
Gold Member
38,009
7,706
I mean I could offer the tips and/or explanations required in the native language of the OP so it's easier for them to read. I don't see how that is against the guidelines.
But your words were "post the answer".
 
Last edited:
  • #9
gneill
Mentor
20,945
2,886
I mean I could offer the tips and/or explanations required in the native language of the OP so it's easier for them to read. I don't see how that is against the guidelines.
I interpreted your use of "answer" to mean "reply".
The forum rules state that the language used for posting must be English.
 
  • Like
Likes CharlieCW and Chestermiller
  • #10
haruspex
Science Advisor
Homework Helper
Insights Author
Gold Member
38,009
7,706
I interpreted your use of "answer" to mean "reply".
But that would be "an answer", not "the answer".
 
  • #11
gneill
Mentor
20,945
2,886
But that would be "an answer", not "the answer".
And that I'd put down to language/translation issues :smile:
I try to be a little flexible when it appears that the poster's first language is not English.
 

Related Threads on Series of masses and pulleys

  • Last Post
Replies
4
Views
786
  • Last Post
Replies
2
Views
2K
  • Last Post
Replies
27
Views
2K
Replies
5
Views
264
  • Last Post
Replies
8
Views
10K
  • Last Post
Replies
6
Views
3K
  • Last Post
Replies
10
Views
1K
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
1
Views
2K
Replies
1
Views
2K
Top