Analyzing a constraint eqn for a pulley system

AI Thread Summary
The discussion focuses on creating the constraint equation for a pulley system, specifically addressing confusion about why the last three variables are divided by two. It is clarified that this division occurs because the second pulley is influenced by two strings, effectively halving the distance from the ground. Additionally, the system can be analyzed as a mechanism of instantaneous levers, with the anchored pulley acting as a type 1 lever and the movable pulley as a type 2 lever. This mechanical advantage impacts the relationship between the pulleys. Understanding these mechanics is crucial for accurately formulating the constraint equation.
guyvsdcsniper
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Homework Statement
Masses M1 and M2 are connected to a system of strings and pulleys
as shown. The strings are massless and inextensible, and the
pulleys are massless and frictionless. Find the acceleration of M1
Relevant Equations
f=ma
I am having trouble creating the constraint equation for this pulley system.

I don't understand why the last 3 variables of the following constraint is divided by 2?

Could anyone help me understand why this is?

Screen Shot 2022-02-10 at 1.45.07 PM.png
 
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quittingthecult said:
I don't understand why the last 3 variables of the following constraint is divided by 2?
That term represents the distance of the second pulley from ground level. (The entire expression is equivalent to saying that the height of the first pulley is fixed.)
 
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Doc Al said:
That term represents the distance of the second pulley from ground level. (The entire expression is equivalent to saying that the height of the first pulley is fixed.)
Oh I see. So since there are two strings connected to the second pulley, that distance is halved?
 
quittingthecult said:
So since there are two strings connected to the second pulley, that distance is halved?
Right.
 
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quittingthecult said:
...
I am having trouble creating the constraint equation for this pulley system.

I don't understand why the last 3 variables of the following constraint is divided by 2?

Could anyone help me understand why this is?
You can also analyze the system as a mechanism of instantaneous levers.
The anchored pulley works as a type 1 lever (mechanical advantage = 1).
The movil pulley works as a type 2 lever (mechanical advantage = 2 for M2 respect to M1, or 0.5 for M1 respect to M2).

1644599743788.png
 
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