Translational and Rotational Equilibrium

[greenseeking]

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A beam has a mass that is uniformly distributed over its length. the beam is placd on supports in one of the two ways below:
Please see attached picture.

What can you conclude about beam i and ii? Anwer is D.

Ok my question is, Why is Beam II not in translational equilibrium? It's unbalanced so it's going to rotate... so it doesn't have Rotational equilibrium. but I don't see it moving in any x or y direction.

Thank you!!

 

[ouroboros39]

It makes a little more sense if you consider only the center of mass of the beam, which would be a little to the right of both the pivots in both the pictures. When the beam begins rotating about the right-most pivot, the center (of mass) will go down a little bit. If there was translational equilibrium, the center of mass should have stayed in the same place - which would indicate no net force on the object (although there could still be a net torque). This was a pretty difficult question - I would have gotten it wrong too since the terms get kind of specific. 🙁

 

[greenseeking]

It makes a little more sense if you consider only the center of mass of the beam, which would be a little to the right of both the pivots in both the pictures. When the beam begins rotating about the right-most pivot, the center (of mass) will go down a little bit. If there was translational equilibrium, the center of mass should have stayed in the same place - which would indicate no net force on the object (although there could still be a net torque). This was a pretty difficult question - I would have gotten it wrong too since the terms get kind of specific. 🙁

thanks-- ur explanation helped! still a little bit confusing problem though!