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Help on moments watch

1. I had no problems doing part a) and part b) but for part c) i was unsure of the method first I did Tsin45 > 10m to get 26.9kg meaning 6.9kg additional but the answer is 6.5kg? I don't think my method was correct. Any ideas? Thanks
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2. (Original post by raiden95)
I had no problems doing part a) and part b) but for part c) i was unsure of the method first I did Tsin45 > 10m to get 26.9kg meaning 6.9kg additional but the answer is 6.5kg? I don't think my method was correct. Any ideas? Thanks
The anticlockwise moment is T sin (45) x 1.5
The clockwise moment is 10m x 2
3. (Original post by Stonebridge)
The anticlockwise moment is T sin (45) x 1.5
The clockwise moment is 10m x 2
I did the calculation again using that but my answer is not 6.5kg :/
4. Have you maybe used g as 9.81 when the question says assume g=10? Just a thought, it might explain a small error like that
5. (Original post by bugsuper)
Have you maybe used g as 9.81 when the question says assume g=10? Just a thought, it might explain a small error like that
I used 10
6. (Original post by raiden95)
I did the calculation again using that but my answer is not 6.5kg :/
Show us what you did.
I get the answer 26.51kg for M (using g=10) giving the answer 6.5kg
7. Well since T=380

1.5x380xsin45 = 20m
So m = 20.2kg
8. (Original post by Stonebridge)
Show us what you did.
I get the answer 26.51kg for M (using g=10) giving the answer 6.5kg
Am I supposed to just make them equal to each other and find m?
9. (Original post by raiden95)
Am I supposed to just make them equal to each other and find m?
Yes. The limiting case where the string breaks is when the clockwise moment from the larger mass is equal to the max anticlockwise moment the string can provide.
10. (Original post by Stonebridge)
Yes. The limiting case where the string breaks is when the clockwise moment from the larger mass is equal to the max anticlockwise moment the string can provide.
Can you check my working please
11. (Original post by raiden95)
Can you check my working please

You put T=380N
The question says the limiting tension is 500N
So put T=500N not 380N
12. (Original post by Stonebridge)
You put T=380N
The question says the limiting tension is 500N
So put T=500N not 380N
Sorry about that I didn't read that, thanks for pointing it out

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