Zero equilibrium 0 x a force?

[j1ceasar]

Okay - a classic trap . multiplication times zero .
I have a 3 foot bar weighing 10 lbs . its attached along its mid point to an axle . how much torque / force - do I need along its axle ( motorized ) to get it to spin 30 rpm or 60 rpm ?

its in equilibrium , but of course it needs FORCE to move it

I am considering Nema class stepper motors / geared 5/1 - 16 to one or 27/1 - usually these motors go to 700- rpm ...

 

[phinds]

Okay - a classic trap . multiplication times zero .
I have a 3 foot bar weighing 10 lbs . its attached along its mid point to an axle . how much torque / force - do I need along its axle ( motorized ) to get it to spin 30 rpm or 60 rpm ?

its in equilibrium , but of course it needs FORCE to move it

I am considering Nema class stepper motors / geared 5/1 - 16 to one or 27/1 - usually these motors go to 700- rpm ...

Uh ... WHAT multiplication by zero?

 

[Mech_Engineer]

Just like F = m*a for linear motion, there is an analog for rotational motion as well. A torque will be required to accelerate the bar, but once it's moving only air drag and friction will slow it down.

See here: https://en.wikipedia.org/wiki/Angular_acceleration