Understanding Equilibrium: Analyzing Two Boxes in Balance

[CountFleet]

Are these two boxes in equilibrium?

 

[berkeman]

Are these two boxes in equilibrium?

What is the context of the question? Is it for a class? What do you think?

 

[CountFleet]

I'm not taking a physics class right now. I'm just trying to learn on my own. I think there in equilibrium.

 

[berkeman]

I'm not taking a physics class right now. I'm just trying to learn on my own. I think there in equilibrium.

Fair enough. I would think they are in equilibrium as well, since the system seems balanced. Even if the mass of the ropes is not negligible, the system still seems balanced.

 

[russ_watters]

Note, though, we don't know the weight of the boxes and regardless of their weight (unless they are negligible too), the ropes they are attached to can't be horizontal - they must sag.

 

[sfsy1]

Why do they have to sag? I thought there's tension?

 

[cjl]

In order for the sag to be zero, the tension would have to be infinite (or the boxes would have to be massless). This is because the vertical component of the tension is supporting the boxes, and if the rope is horizontal, the vertical component is zero.

 

[CountFleet]

Thanks for all the replys! :) The way I have it though when you move one box the other one gets pulled in the opposite direction. Is there a way to get both boxes to move in the same direction?

 

[russ_watters]

Slack the ropes and push on the boxes directly or move the pulleys.

 

[CountFleet]

Wouldn't slag put it out of equilibrium? How could you change the pulleys so both boxes can move in equilibrium in the same direction at the same time?