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# M2 centre of mass watch

1. can someone please tell me how to find the cntre of mass of a semi-circle
2. (Original post by poiuyt)
can someone please tell me how to find the cntre of mass of a semi-circle
its in the formula book.
3. the edexcel 1?
4. I think it's 4r/3pi from the straight edge along the line of symmetry.
5. (Original post by poiuyt)
the edexcel 1?
oops sorry i assumed u was doing edexcel for some reason.
yes its in the edexcel one.
6. You don't need to know how to do that until M3. Just use what's in the formula book.

God, it's amazing the sort of stuff they give in the formula book when you look at the stuff they neglect to include. They will tell you, for instance, that (coshx)^2 - (sinhx)^2 = 1, but they won't tell you the vector formulae (volume of shapes, etc) - the sort of stuff you don't really want to remember.
7. (Original post by K'uin K'ra)
You don't need to know how to do that until M3. Just use what's in the formula book.
If I remember rightly, they don't give you an equation specifically for the centre of mass of a semi-circle, but for a sector of a circle and you have to use 2α = π radians or something.
8. (Original post by K'uin K'ra)
You don't need to know how to do that until M3. Just use what's in the formula book.

God, it's amazing the sort of stuff they give in the formula book when you look at the stuff they neglect to include. They will tell you, for instance, that (coshx)^2 - (sinhx)^2 = 1, but they won't tell you the vector formulae (volume of shapes, etc) - the sort of stuff you don't really want to remember.
you do need to know how to find the centre of mass of a semi circle in edexcel M2, maybe u r doing a different board?
its in the formula book, but just make sure u know how to use it.
9. (Original post by Nylex)
If I remember rightly, they don't give you an equation specifically for the centre of mass of a semi-circle, but for a sector of a circle and you have to use 2α = π radians or something.
Yes, you're right. So you do have to think for yourself a little. :P
you do need to know how to find the centre of mass of a semi circle in edexcel M2, maybe u r doing a different board?
its in the formula book, but just make sure u know how to use it.

Yes, you have to calculate the centre of mass, but using a formula given. In M3 you're required to prove it from first principles. That's what I meant, I suppose I didn't really make myself clear. Sorry about that.

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Updated: June 23, 2004
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