Physics Help Forum direction of normal reaction

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 Aug 31st 2017, 11:36 AM #1 Junior Member   Join Date: Aug 2017 Posts: 2 direction of normal reaction hi i was wondering if someone could help me on something based on this thread. statics in general when i look at these type of static questions ( with a object touch a sphere/circle) I am not sure what direction the normal reaction is supposed to be. I understand that it depends on if you are looking at forces on the sphere or if you are looking at forces on the object. sometimes the question makes it clear what they are looking for. for example part (i) of a question would say draw a diagram of all the forces on the sphere. but sometimes they do not. some times they will will just give you a big diagram and ask you to prove something and it might not give you an indication. when i am letting forces up/right=forces down/left i am not sure what direction the normal reaction should be. i also get this problem when taking moments. how are you supposed to know? thanks
 Sep 1st 2017, 03:02 AM #2 Senior Member     Join Date: Jun 2016 Location: England Posts: 366 There is not much assistance I can give to your post, it is just too vague. possibly if you could post a specific example, we can work on that and then perhaps move on the more general issue. Always (unless the teacher/lecturer has made a mistake) the question should contain all the information you need. However sometimes they are a bit sneaky and disguise or camouflage the information you need. Perhaps they are presenting the information in a way you are not used to or in a way you are not expecting (quite possibly a way they have not included in previous example questions you have been shown). Read through the problem again, very carefully. Look for anything you might have missed, or misinterpreted, or something you might not have recognised the significance of. __________________ ~\o/~

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