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# Can you solve this mechanics question? watch

1. They are all equilateral triangles

need to find reactions and internal forces
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2. (Original post by icantdomaths)
They are all equilateral triangles

need to find reactions and internal forces
You mean can we do your homework for you?

How about you show us what you've got so far, what you think the method is, where you're getting stuck. Just give us something to show you've actually attempted the question instead of looking at it, deciding it's a bit difficult and asking us all to solve it for you.
3. the point is i don't even know where to begin.
4. i dont do a-level maths its for a project
5. (Original post by icantdomaths)
They are all equilateral triangles

need to find reactions and internal forces
I will look at this tomorrow
(not in a fit state now ...)
6. (Original post by mackemforever)
You mean can we do your homework for you?

How about you show us what you've got so far, what you think the method is, where you're getting stuck. Just give us something to show you've actually attempted the question instead of looking at it, deciding it's a bit difficult and asking us all to solve it for you.
I have no idea why people on this site prefer to be condescending than to actually help someone that needs it or suggest nicely that some work should be shown first. Maybe you could've at least given the first step with explanation so that they'll feel like they're getting somewhere. Your condescension isn't helping.
7. (Original post by icantdomaths)
They are all equilateral triangles

need to find reactions and internal forces
please post a photo of the actual question
8. (Original post by icantdomaths)
They are all equilateral triangles

need to find reactions and internal forces
I'm not sure what the symbols at the top left and right mean. Presumably they're used in engineering?

Having said that, you need to assigns tensions to each member of the truss, then form and solve simultaneous equations in the tensions. Bear in mind that the truss and all joints are in translational and rotational equilibrium, so at each joint, Newton II gives and you have about any point for the whole truss.

It looks like quite a lot of work to find all of the tensions though. If you're only interested in one of the members, you can use the method of sections to isolate it, but I can't remember how that works, in detail.
9. (Original post by atsruser)
I'm not sure what the symbols at the top left and right mean. Presumably they're used in engineering?

Having said that, you need to assigns tensions to each member of the truss, then form and solve simultaneous equations in the tensions. Bear in mind that the truss and all joints are in translational and rotational equilibrium, so at each joint, Newton II gives and you have about any point for the whole truss.

It looks like quite a lot of work to find all of the tensions though. If you're only interested in one of the members, you can use the method of sections to isolate it, but I can't remember how that works, in detail.
I've actually only seem those symbols in my degree.

The one they're pinned, fixed and rollers.

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10. (Original post by ServantOfMorgoth)
I've actually only seem those symbols in my degree.

The one they're pinned, fixed and rollers.

Posted from TSR Mobile
So presumable a roller symbol means that at that joint, it can only supply a normal reaction force, but no transverse force?
11. (Original post by atsruser)
So presumable a roller symbol means that at that joint, it can only supply a normal reaction force, but no transverse force?
It's more about freedom of movement. Rollers means that it can literally roll so it has lateral movement.

Fixed usually means one end is fixed so only movement in one direction (think cantilever)

And pinned means it can't move at all.
12. (Original post by ServantOfMorgoth)
It's more about freedom of movement. Rollers means that it can literally roll so it has lateral movement.
I don't see how that joint could move anyway. The truss is fixed at the top left, isn't it? In which case, the only point I can see of the roller is to restrict the force to a reaction force. But I'm not an engineer so maybe I'm confused.
13. (Original post by atsruser)
I don't see how that joint could move anyway. The truss is fixed at the top left, isn't it? In which case, the only point I can see of the roller is to restrict the force to a reaction force. But I'm not an engineer so maybe I'm confused.
Yeah it's probably a part of a larger system so you need not boggle your mind on how it'll move for the analysis of the problem. It's more about the number of equations you'll need to develop to solve it. There's at least 2 ways to solve this, none of which I remember at the moment

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