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# M2 Statics Help Please. watch

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1. Attachment 519281519283

Hi,I need help determining the direction of the reaction force on the rod for this question. I drew it as so in the picture and saw there for be a net force to the right when looking at the horizontally component only, thus the rod would accelerate to the right. However, I don't quite understand how this could be if the rod is in equilibrium.

My other thought is that the reaction force would act diagonally towards the top left of the paper or diagonally towards the bottom left of the paper. But, I don't understand how a reaction force can act in towards the wall. Can someone please explain how to determine the direction of the reaction force please?

Thanks for the help!
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2. (Original post by Glavien)
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I'm not sure I understand, you've said horizontal force: , i.e: there is no net resultant force towards the right, hence why you equated it to zero. What's confusing you?
3. (Original post by Zacken)
I'm not sure I understand, you've said horizontal force: , i.e: there is no net resultant force towards the right, hence why you equated it to zero. What's confusing you?
According to my diagram if you consider forces horizontally only, there is a thrust component to the right and a reaction component to the right. Thus, a net force to the right. So, to maintain in equilibrium shouldn't there be an additional force to the left? Sorry, its a bit confusing.
4. (Original post by Glavien)
According to my diagram if you consider forces horizontally only, there is a thrust component to the right and a reaction component to the right. Thus, a net force to the right. So, to maintain in equilibrium shouldn't there be an additional force to the left? Sorry, its a bit confusing.
I see your problem, remember that the pole is hinged to A, so your reaction vertically should be upwards (doesn't really matter though, the algebra will sort itself out) and the reaction horizontally should be towards the left, you've done downwards and rightwards respectively when it's upwards and leftwards.
5. (Original post by Zacken)
I see your problem, remember that the pole is hinged to A, so your reaction vertically should be upwards (doesn't really matter though, the algebra will sort itself out) and the reaction horizontally should be towards the left, you've done downwards and rightwards respectively when it's upwards and leftwards.
Yeah, I think I got it. I should get negative values at the end indicating the reaction force is to the left and upwards. Thank you, your help is much appreciated!
6. (Original post by Glavien)
Yeah, I think I got it. I should get negative values at the end indicating the reaction force is to the left and upwards. Thank you, your help is much appreciated!
Yep, that's what (I think) is going on!
7. (Original post by Glavien)
Attachment 519281519283

Hi,I need help determining the direction of the reaction force on the rod for this question. I drew it as so in the picture and saw there for be a net force to the right when looking at the horizontally component only, thus the rod would accelerate to the right. However, I don't quite understand how this could be if the rod is in equilibrium.

My other thought is that the reaction force would act diagonally towards the top left of the paper or diagonally towards the bottom left of the paper. But, I don't understand how a reaction force can act in towards the wall. Can someone please explain how to determine the direction of the reaction force please?

Thanks for the help!
The rod is hinged to the wall at A, not just resting in contact. The force at a hinge can go in any direction (go and have a look at a hinge), so can (needs to) pull the rod towards the wall.
8. (Original post by Glavien)
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(Original post by Zacken)
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I think you'll find the reaction at A is left and downwards.

Consider moments about D - though the OP may not have covered this yet in their course
9. (Original post by tiny hobbit)
The rod is hinged to the wall at A, not just resting in contact. The force at a hinge can go in any direction (go and have a look at a hinge), so can (needs to) pull the rod towards the wall.
Thanks for the help.
10. (Original post by ghostwalker)
I think you'll find the reaction at A is left and downwards.

Consider moments about D - though the OP may not have covered this yet in their course
Yep, it should be downwards, thanks!

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