I Cylinder supported by two rollers

[dada1]

I'm trying to calculate the static reaction force on cylinder supported by two rollers due to the weight of the cylinder. I found that the reaction force is inversely proportional to the Cosine of the contact angle, but what does it mean? when the contact angle is close to 90 degrees is the reaction force much higher then the weight of the cylinder? if the weight of the cylinder is the source of the reaction forces how can it be lower than the reaction forces?

 

[BvU]

Hi dada, !

Are you aware that certain components of the reaction force oppose each other ?

And: is this homework ?

 

[dada1]

But still -the non opposing reaction components are much higher then their "source" - the weight of the cylinder. I just wonder how can it be (and its not homework..)

 

[BvU]

Compare it with holding up a weight hanging from the middle of a wire by pulling apart the two ends. There's a $1/\cos$ in there too ...

 

[sophiecentaur]

the source of the reaction forces

This is the Trojan Horse in your question. Forces don't have a "source". Energy and Work have sources. Cause and effect follow a logical direction and Energy 'flows'. Forces are merely 'there'. Large forces can turn up when a small force is applied in many circumstances. That's the basis of most tools we use from levers to screw jacks.