# Homework Help: A,B,C and D are 4 beams what beam we can change it to chain and this system till

1. Mar 12, 2012

### zizodev

1. The problem statement, all variables and given/known data

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?

2. Mar 12, 2012

### tiny-tim

hi zizodev!

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

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

3. Mar 12, 2012

### zizodev

Re: A,B,C and D are 4 beams ..what beam we can change it to chain and this system t

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.:)

4. Mar 12, 2012

### tiny-tim

hi zizodev!
give a reason!

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

5. Mar 13, 2012

### zizodev

Re: A,B,C and D are 4 beams ..what beam we can change it to chain and this system t

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...

6. Mar 13, 2012

### tiny-tim

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?

7. Mar 13, 2012

### zizodev

Re: A,B,C and D are 4 beams ..what beam we can change it to chain and this system t

the B are in tension i think..:)

8. Mar 13, 2012

### tiny-tim

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

9. Mar 13, 2012

### zizodev

Re: A,B,C and D are 4 beams ..what beam we can change it to chain and this system t

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