Changing A,B,C and D Beams to Chain for Perfect System Performance

[zizodev]

Homework Statement

http://data.imagup.com/10/1146211599.jpg

A,B,C and D are 4 beams ..what beam we can change it to chain and this system till stay work perfectly?

 

[tiny-tim]

hi zizodev!

tell us what you think, and then we'll comment!

(and are the beams hinged, or rigidly jointed?)

 

[zizodev]

emm..i think rigidly jointed and for me the changeable one is C..isn't..let me know the 2 case (for the beams hinged and rigidly jointed)
thank you tiny-tim in advance.:)

 

[tiny-tim]

hi zizodev!

..what beam we can change it to chain and this system till stay work perfectly?

… for me the changeable one is C..

give a reason!

(when can you replace a beam by a chain? )

 

[zizodev]

i have chosen C because i felt that this is less important ! and i haven't no idea about mechanical design. about mechanical strengths etc...

 

[tiny-tim]

(when can you replace a beam by a chain? )

a beam can have either tension or compression

a chain can only have tension

(you can't push a chain, can you? )

so a chain can only replace a beam in tension

so you'll need to prove: which beams are in tension? ​

 

[zizodev]

the B are in tension i think..:)

 

[tiny-tim]

yes, but the difficulty is that if you replace B by a chain, what is there to stop A falling?

 

[zizodev]

hahah...so the final answer will be C ...thnks again tiny-tim