Rest vs Equilibrium

[anbuitachi]

In the TBR, it says for a rigid body to be at rest, both translation acceleration and rotational accleration must be 0.

For a rigid body to be in equilibrium, both net torque and net force must be 0.

What is the difference? I thought if Net force and torque are both 0, then the acceleration is also 0.. so isn't it saying rest = equilibrium?

EDIT: just noticed i posted in the wrong place -_-, should be in Q/A

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[fhgoalie15]

i could be wrong... but i think the key word is 'net' cuz you can still be moving (ie. not at rest) but end up having no NET movement (like ending up right where you started), which puts you at equilibrium... is that what you mean?

 

[SN2ed]

Thread moved. These topics belong in the Study Q&A forum.

 

[RogueUnicorn]

rest is just a special case of equilibrium where there is no motion

 

[anbuitachi]

oh so both velocity and acceleration should be at 0 at rest

 

[Isoprop]

Yes.

Think of a hammer in space. If it's just sitting there, it's at rest and in equilibrium.

If I fling it and it's moving and rotating at a constant velocity, it's not at rest anymore, but it's still in equilibrium.