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# Unsure about force diagram - rigid bodies

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1. Hi, I'm stuck on a force diagram because I'm not sure how a hinge impacts it. The question itself can be found here http://i.imgur.com/KMCXnla.png.

I've split into to separate diagrams each with a normal reaction to the floor; the weight coming from the middle of the ladder and the tension from the string. Is there a reaction force from the hinge? Where would it point?

Any help would be appreciated a lot.
2. (Original post by Heywhatsgood)
Hi, I'm stuck on a force diagram because I'm not sure how a hinge impacts it. The question itself can be found here http://i.imgur.com/KMCXnla.png.

I've split into to separate diagrams each with a normal reaction to the floor; the weight coming from the middle of the ladder and the tension from the string. Is there a reaction force from the hinge? Where would it point?

Any help would be appreciated a lot.
Yes, there is a reaction at the hinge. How do you know that? Becasue if the hinge wasn't there, the ladders would fall flat.

Best way, IMO to look at the hinge is to break the reaction down into horizontal and vertical components.

Considering the horizontal.

If the hinge wasn't there which way would the ladder fall? Right or left? Reaction at hinge must be in the opposite direction.

Considering the vertical.

This is a little trickier. By symmetry the vertical component must be the same for each of the ladders (in magnitude and direction). But since the hinge isn't moving the vertical component for one ladder must be equal and opposite to the vertical component on the other ladder. There is only one value for the vertical force that satisfies these two properties. Any thoughts?

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