Analyzing Mass A's Direction of Motion

[Steve4Physics]

Another way to get the initial direction is to consider the height of the system's centre-of-gravity (CoG).

When released from rest, the CoG must move downwards, converting gravitational potential energy to kinetic energy (and to heat).

This happens when the height of the heavier object (B) decreases and the height of the lighter object (A) increases.

(If the CoG moved upwards, this would violate the conservation of energy: gravitational potential energy, kinetic energy and heat would need to be created out of nowwhere.)

 

[kuruman]

There is also friction between the blocks. This of course represents a 3rd law pair but once you straighten the string they act in the same direction because one is turned 180 degrees.

Yes, of course, this makes much more sense. I assumed without thinking that the frictions would cancel like the tensions although it didn't sit well with me because of what happens when the incline is frictionless but there is friction between blocks. My excuse of the day is that my wife was pressuring me to do something for her so I posted in a hurry.

 

[Orodruin]

My excuse of the day is that my wife was pressuring me to do something for her so I posted in a hurry.

Add to end of post:
"This post is dedicated to my dear beloved wife."