Why are the coordinate axis different for block M1 and M2 in this scenario?

[Miike012]

I am confused how they picked the direction right of block M1 to be -x and the downward direction of block M2 to be +x..?

I didn't know that one could create two different coordinate axis.

Correct me if I am wrong but it seems that if you are working with two diff body's that are not in contact you can create diff axis for both body's.. but if two body's are in contact then you have to use the same axis for both body's?

 

[gneill]

What's block M1? What's block M2? What are they up to? Who are "they"? Without context, your statements are vague and your questions unanswerable.

 

[Miike012]

sorry forgot to add the picture... here it is..

 

[gneill]

Okay. In this situation there are two separate objects being considered. They are connected by a string (or rope, or cable, or however it's defined). Because they are so connected, their motions are coupled. That is, any change of displacement of one is going to be identical to the displacement of the other, in magnitude if not direction. This being so, it would make sense to choose the same variable name for both displacements (they will have equal values at all times). x is the value of the horizontal displacement of block M1, and it's also the vertical displacement of block M2. Does that work for you?

 

[rwisz]

There are a few possible explanations for why the coordinate axis may be different for block M1 and M2 in this scenario. One possibility is that the blocks are in different orientations relative to each other, so the coordinate axis are chosen to align with the direction of motion or forces for each block. Another possibility is that the blocks have different masses or properties, so the coordinate axis are chosen to account for these differences.

In general, the choice of coordinate axis is arbitrary and can vary depending on the specific situation or problem being studied. As long as the chosen axis are consistent and clearly defined, it should not affect the overall analysis or results. And you are correct that when two bodies are in contact, it is typically necessary to use the same coordinate axis for both bodies in order to accurately describe their interactions.

I hope this helps clarify the reasoning behind the different coordinate axis in this scenario. As a scientist, it is important to carefully consider and define the coordinate system being used in order to accurately analyze and interpret data.