I came across a Statics problem on the web which doesnt seem

I came across a Statics problem on the web which doesn\'t seem correct to and it\'s bugging me. The problem in the link is for a doorframe mounted chin up bar. The problem accounts for three vertical forces, Oy, Ry and W, and only one horizontal force, Rx. This certainly seems to be missing the force Ox. I can\'t imagine a scenario where there would be zero force at O in the x. Wouldn\'t that either suggest an imbalanced force or zero force at R in the x as well? Thank you for taking a look. Here\'s the link http://mindtribe.com/2011/07/tim-is-wrong-about-my-pull-up-bar/

Solution

The scenario seems interesting and your concern for the reaction forces could be dealt with in three ways,

1) An hinged support at O - this results in a Ov along Y and Or along X which means a resultant reactant forces restricts the motion of the joint.

2) A fixed support at O - considering a fixed support adds up a fixing moment Mo at that point along with Ov and Or which means a resulant forces with net restricting moment.

3) A simple support at O - could be imagined as a photo frame hanging on wall. The nail only holds the frame from falling down or imparts a reaction force Ov and not fixes it moment nor its horizontal motion.