- #1
pryphnoq
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I need to settle an argument between two mech eng colleagues... Here goes.
There is an infinitely rigid beam running between two walls. The attachment points are fixed. There is a force acting downwards on the center of the beam. The disagreement is on whether there is a reactive torque in the fixing points.
One side argues that, due to the infinite rigidity, there will only be straight, downwards forces - effectively exerting shearing on the fixing point.
The other side argues that, since there is a lever arm (1/2 of the beam) and a perpendicular force, there is torque. There always is. The infinite rigidity is moot.
So, who's right?
Also: the example is of course highly theoretical. What happens in a practical scenario, where the beam is not infinitely rigid, but just comparatively very, very rigid...?
There is an infinitely rigid beam running between two walls. The attachment points are fixed. There is a force acting downwards on the center of the beam. The disagreement is on whether there is a reactive torque in the fixing points.
One side argues that, due to the infinite rigidity, there will only be straight, downwards forces - effectively exerting shearing on the fixing point.
The other side argues that, since there is a lever arm (1/2 of the beam) and a perpendicular force, there is torque. There always is. The infinite rigidity is moot.
So, who's right?
Also: the example is of course highly theoretical. What happens in a practical scenario, where the beam is not infinitely rigid, but just comparatively very, very rigid...?