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# M1 Moments watch

1. A uniform beam of length 2m and mass 4kg has a mass 3kg attached at one end and a mass of 1kg at the other end. Find position of the pivot if the beam rests in equilibrium in a horizontal position.

help.... this is due in 2 hours and 5 minutes from the time of this post TeeEm Zacken Student403
2. Which part are you stuck on?
3. (Original post by Student403)
Which part are you stuck on?
so far i've drawn a beam with 3g at one end and 1g on the other, in the centre i've put 4g going down and i've labelled the distances as 1m from 4g to either side of the beam
4. (Original post by thefatone)
so far i've drawn a beam with 3g at one end and 1g on the other, in the centre i've put 4g going down and i've labelled the distances as 1m from 4g to either side of the beam
Draw the pivot and add a reaction force from the pivot as well. Then take moments from one of the ends. You'll need to resolve vertically to find the reaction force from the pivot.
5. (Original post by thefatone)
so far i've drawn a beam with 3g at one end and 1g on the other, in the centre i've put 4g going down and i've labelled the distances as 1m from 4g to either side of the beam
Good going

Now you need to remember that since there's one pivot, the reaction force upwards is equal to the entire weight of everything downwards from the beam. What's the exact value of that?

Also, why don't you let x = the distance of the pivot from a chosen end. Then you could take moments from that end to find the value of x
6. (Original post by Zacken)
Draw the pivot and add a reaction force from the pivot as well. Then take moments from one of the ends. You'll need to resolve vertically to find the reaction force from the pivot.
(Original post by Student403)
Good going

Now you need to remember that since there's one pivot, the reaction force upwards is equal to the entire weight of everything downwards from the beam. What's the exact value of that?

Also, why don't you let x = the distance of the pivot from a chosen end. Then you could take moments from that end to find the value of x
there's a pivot? o.o that's at the 4g right? i guess that's what i was missing >.>
7. (Original post by thefatone)
A uniform beam of length 2m and mass 4kg has a mass 3kg attached at one end and a mass of 1kg at the other end. Find position of the pivot if the beam rests in equilibrium in a horizontal position.

help.... this is due in 2 hours and 5 minutes from the time of this post TeeEm Zacken Student403
8. (Original post by thefatone)
there's a pivot? o.o that's at the 4g right?
No, they're asking you to find the position of the pivot, see my diagram.
9. (Original post by thefatone)
there's a pivot? o.o that's at the 4g right? i guess that's what i was missing >.>
No the pivot is where you have to work out. See Zain's drawing
10. (Original post by Zacken)
No, they're asking you to find the position of the pivot, see my diagram.
Damn you've beat me 2/2 times
11. (Original post by Student403)
Damn you've beat me 2/2 times
Nah, you got the first post.

Edit: wait for TeeEm's comment.
12. (Original post by Zacken)
Nah, you got the first post.

Edit: wait for TeeEm's comment.
Aww bless!
13. (Original post by Zacken)
right oh okay the question is phrased slightly different to how i would normally see them in the textbook, usually in the textbook they call the unknown distance x or something Thanks a bunch
14. (Original post by thefatone)
right oh okay the question is phrased slightly different to how i would normally see them in the textbook, usually in the textbook they call the unknown distance x or something Thanks a bunch
Good questions are when they are unstructured and you need to pick your own variables and label your own stuff. I prefer those kinds of questions, you'll need to get used to it. No problem! :-)
15. (Original post by Student403)
No the pivot is where you have to work out. See Zain's drawing
Thanks a bunch too!
(Original post by Zacken)
Good questions are when they are unstructured and you need to pick your own variables and label your own stuff. I prefer those kinds of questions, you'll need to get used to it. No problem! :-)
it's the first time i've done these kind of unstructured questions for moments xD
16. (Original post by thefatone)
Thanks a bunch too!

it's the first time i've done these kind of unstructured questions for moments xD
Np
17. (Original post by Student403)
Np
I love how this thread has like 16 views and 15 replies.
18. (Original post by Zacken)
I love how this thread has like 16 views and 15 replies.
Efficiency at its finest
19. (Original post by Student403)
Np
(Original post by Zacken)
I love how this thread has like 16 views and 15 replies.
i got the distance as 6/13 metres is that right?
20. (Original post by thefatone)
i got the distance as 6/13 metres is that right?
I don't think so (did it in my head so you might very well be right), no, did you get ?

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