# Centre of massWatch

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#1

Could someone solve this in another way because I got an answer of 0.53, but the answer at the back is root 5 over 5

Thanks
0
4 weeks ago
#2
(Original post by SeverusESnape)

Could someone solve this in another way because I got an answer of 0.53, but the answer at the back is root 5 over 5

Thanks
Can you upload your attempt? I get the same as the book.
Last edited by mqb2766; 4 weeks ago
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#3
(Original post by mqb2766)
Can you upload your attempt? I get the same as the book.
0
#4
(Original post by mqb2766)
Can you upload your attempt? I get the same as the book.
May I see what you've done...?
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#5
(Original post by mqb2766)
Can you upload your attempt? I get the same as the book.
0
4 weeks ago
#6
I started by assuming that the origin is at C.
So (by symmetry) the horizontal com is zero and the vertical com is the distance.
So work out the vertical com in terms of the midpoints of the sides. Side 4 drops out.
Does that help any?
Last edited by mqb2766; 4 weeks ago
0
#7
(Original post by mqb2766)
I started by assuming that the origin is at C.
So (by symmetry) the horizontal com is zero and the vertical com is the distance.
So work out the vertical com in terms of the midpoints of the sides. Side 4 drops out.
Does that help any?
So you just changed the origin and got the right answer? I'm out by like 0.1 because root 5 over 5 is 0.4... I just chose A as my origin which SHOULD give me root 5 over 5. Can you post your working? Have you rounded your values?
0
4 weeks ago
#8
(Original post by SeverusESnape)
So you just changed the origin and got the right answer? I'm out by like 0.1 because root 5 over 5 is 0.4... I just chose A as my origin which SHOULD give me root 5 over 5. Can you post your working? Have you rounded your values?
Tbh, I didn't fully understand your working. Can you annotate it to explain it a bit better. I didn't round, as using surds was reasonably straightforward.

You're correct, that it should not matter where the origin is, but placing it at C is an obvious place which simplifies the calculation. If I was you, I'd try reworking it with the origin at C. Happy to help you with your work, but I'm not posting solutions.
Last edited by mqb2766; 4 weeks ago
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#9
.....
Last edited by SeverusESnape; 4 weeks ago
0
4 weeks ago
#10
(Original post by SeverusESnape)
Can someone solve it and post their working please
The forum rules say the maths forum is not a homework service. See the sticky at the top.
Last edited by mqb2766; 4 weeks ago
0
#11
(Original post by mqb2766)
The forum rules say the maths forum is not a homework service. See the sticky at the top.
Last edited by SeverusESnape; 4 weeks ago
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