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M3 question help watch

1. Can anyone help me see where I'm going wrong in this question, it's January 2014 IAL Q5. It's gotten to the point where I've convinced myself I'm right even though I know I'm wrong 😓
2. I would help but I haven't done this paper yet and I don't want to ruin it as a mock.

Maybe Zacken can help you. Zacken
3. (Original post by Nathanbh321)
Can anyone help me see where I'm going wrong in this question, it's January 2014 IAL Q5. It's gotten to the point where I've convinced myself I'm right even though I know I'm wrong 😓
where is the question?
4. (Original post by Nathanbh321)
Can anyone help me see where I'm going wrong in this question, it's January 2014 IAL Q5. It's gotten to the point where I've convinced myself I'm right even though I know I'm wrong 😓

M(O), the weight should be just mg I think, not mg sin theta.
5. (Original post by TeeEm)
where is the question?
Q5 here: https://8a40d6c38bafca75cc407741c0f3...%20Edexcel.pdf
6. (Original post by Zacken)
M(O), the weight should be just mg I think, not mg sin theta.
But then it wouldn't be perpendicular to the line of action of mg, would it? I'm so confused. You could take the sin(a) of the whole thing but that yields the same result 😞
7. (Original post by Nathanbh321)
But then it wouldn't be perpendicular to the line of action of mg, would it? I'm so confused. You could take the sin(a) of the whole thing but that yields the same result 😞
I haven't checked properly - but it's either the fact that your resolving upwards on the first line should be mgsin theta or your weight in your moments equation should be mg. It's one of those two problems, I think
8. (Original post by Nathanbh321)
But then it wouldn't be perpendicular to the line of action of mg, would it? I'm so confused. You could take the sin(a) of the whole thing but that yields the same result 😞

(Original post by Zacken)
I haven't checked properly - but it's either the fact that your resolving upwards on the first line should be mgsin theta or your weight in your moments equation should be mg. It's one of those two problems, I think
If you do not get joy give me a shout and I will post my solution to the paper
9. (Original post by Zacken)
I haven't checked properly - but it's either the fact that your resolving upwards on the first line should be mgsin theta or your weight in your moments equation should be mg. It's one of those two problems, I think
The mg wouldn't give the correct solution either, so it couldn't be that. In the mark-scheme it gives (9/4rsin(theta) - rcos(theta))*mg as the moment, as if the sin(theta) was only applied to the 9/4r. Is that possible?
10. (Original post by TeeEm)
If you do not get joy give me a shout and I will post my solution to the paper
Yeah that would be great, thanks.
11. (Original post by Nathanbh321)
Yeah that would be great, thanks.
let Zacken help you first ...
12. (Original post by Nathanbh321)
The mg wouldn't give the correct solution either, so it couldn't be that. In the mark-scheme it gives (9/4rsin(theta) - rcos(theta))*mg as the moment, as if the sin(theta) was only applied to the 9/4r. Is that possible?
Right - that's exactly what you need to do. 9/4 r sin theta is the perpendicular distance, which is what you need to use for the moment equation.
13. (Original post by Zacken)
Right - that's exactly what you need to do. 9/4 r sin theta is the perpendicular distance, which is what you need to use for the moment equation.
So I tried this and got the same result, cos(theta), 9/4 rsin(theta) is longer than the perpendicular distance so as shown you need to take away rcos(theta)sin(theta)
14. (Original post by TeeEm)
let Zacken help you first ...
Go ahead.
15. (Original post by Zacken)
Go ahead.

(Original post by Nathanbh321)
Yeah that would be great, thanks.
16. (Original post by TeeEm)
Thanks, I felt like something vital was missing. Didn't think of the other component of the weight 😜. Idk what's wrong with my method but I can work with this.
17. (Original post by Nathanbh321)
Thanks, I felt like something vital was missing. Didn't think of the other component of the weight 😜. Idk what's wrong with my method but I can work with this.
It can be done without resolving weights, but then you need to resolve distances
you are looking at my style which might not suit everybody ...
but I think it is very clear since ...
Spoiler:
Show
Nobody does it better
Makes me feel sad for the rest
Nobody does it half as good as you
Baby, you're the best
18. (Original post by TeeEm)
It can be done without resolving weights, but then you need to resolve distances
you are looking at my style which might not suit everybody ...
but I think it is very clear since ...
Spoiler:
Show
Nobody does it better
Makes me feel sad for the rest
Nobody does it half as good as you
Baby, you're the best
This is either a reference to a song I can't quite remember, or you're being very flirtatious
19. (Original post by Nathanbh321)
This is either a reference to a song I can't quite remember, or you're being very flirtatious
you are probably too young
https://www.youtube.com/watch?v=PNA7DcVppEs
20. (Original post by TeeEm;[url="tel:62864231")
62864231[/url]]you are probably too young
https://www.youtube.com/watch?v=PNA7DcVppEs
I didn't know whether they were the lyrics to this or 'you're the best'

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