Doubt about solution -- Two masses connected by a rod moving on a surface

[String theory guy]

Homework Statement

The statement is below.

Relevant Equations

Newton's Second Law

The doubt is about this question.

Which the answer is

They say that all the forces are pulling forces? How is this the case?

How would this setup even work? I don't think block 2 could pull the rod.

 

[haruspex]

They say that all the forces are pulling forces? How is this the case?

Can you find one that isn't?

 

[String theory guy]

Yes I can @haruspex :
F1, rod
F2, rod

 

[haruspex]

Yes I can @haruspex :
F1, rod
F2, rod

F_1,rod is the force m₁ exerts on the rod. That force pulls the rod to the left.

 

[String theory guy]

F_1,rod is the force m₁ exerts on the rod. That force pulls the rod to the left.

I thought it was the opposite way round. How did you derive that @haruspex ?

 

[haruspex]

I thought it was the opposite way round. How did you derive that @haruspex ?

Do you mean, how do I know that F_1,rod is the force m₁ exerts on the rod, not the force the rod exerts on m₁? Because clearly everything does move to the right, and the only way m₁ is going to move to the right is if the force the rod exerts on m₁ is to the right. So that must be F_rod,1.
But the question ought to have made the notation clear.

 

[String theory guy]

Do you mean, how do I know that F_1,rod is the force m₁ exerts on the rod, not the force the rod exerts on m₁? Because clearly everything does move to the right, and the only way m₁ is going to move to the right is if the force the rod exerts on m₁ is to the right. So that must be F_rod,1.
But the question ought to have made the notation clear.

Yea that is my doubt I think @haruspex - how dose everything in the system move to the right? Is there some glue or something between the block and masses? That is the only way I can see mass 1 moving to the right being in contact with the rod that is moving to the right.

I don't know, but the force of static friction should not be that great allowing the rod to pull mass 1.

 

[haruspex]

Is there some glue or something between the block and masses?

It says they're connected, so I would take that as meaning they are somehow secured together.