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Relationship of acceleration in two-pulley system

  • #1

Homework Statement


upload_2015-2-4_20-24-52.png

What is the relationship between a1 and a2
A.a1=a2
B.a1=2a2
C.a2=2a1
D.a1=a2√2
E.a2=a1√2
F.There is no simple relationship between the two acceleration

Homework Equations


a = F/m

The Attempt at a Solution


I am quite confused with the second pulley , so the weight of m2 is divided to 2 tension through the second pulley , but i cant find what is the magnitude of the upper tension ,therefore we cant find the lower tension or the acceleration either.
So i choose F as my answer , however i am not sure . Is my answer right ?.
 
Last edited:

Answers and Replies

  • #2
DEvens
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Conserve string.
 
  • #3
Conserve string.
sorry i dont get it . can you be more specific , and which answer do you choose :D
 
  • #4
DEvens
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Really? That's not enough?

Ok. When mass m1 moves a distance of 1 unit, how far must the mass m2 move?
 
  • #5
That's where i was confused.
If m2 goes a distance of x. Will m1 goes a distance of x/2 or 2x?
 
  • #6
haruspex
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That's where i was confused.
If m2 goes a distance of x. Will m1 goes a distance of x/2 or 2x?
Let the lengths of the horizontal portions be x (on the left), y (top right), z (lower right).
What equations relate them?
 
  • #7
392
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I have the same problem too
Let the lengths of the horizontal portions be x (on the left), y (top right), z (lower right).
What equations relate them?
I think that it is Δx = Δy + Δz
Since Δy is the same as Δz, so Δx = 2Δy = 2Δz
So, a2 = 2a1, right ?
 
  • #8
BvU
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Try again.
 
  • #9
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Try again.
Hmm..
I tried and got the same answer, a2 = 2a1
Please explain the correct answer to me

EDIT :
Tried again and get a1 = 2a2
 
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  • #10
haruspex
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  • #11
Hmm..
I tried and got the same answer, a2 = 2a1
Please explain the correct answer to me

EDIT :
Tried again and get a1 = 2a2
sr i didnt understand , since S = 1/2 at^2
then if Δx=2Δy .
then ax should be equal 2 ay ?
then a2 = 2a1 ?
 
  • #12
haruspex
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sr i didnt understand , since S = 1/2 at^2
That's irrelevant to how the lengths x, y and z relate.
then if Δx=2Δy .
It isn't.
What combinations of lengths x, y and z are known to be constant?
 

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