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# circular motion watch

1. this is my working: http://imgur.com/EbI2aXE

i'm not sure where i'm going wrong, or how to do the question as it specified.
2. Feel sorry for you. I can't even draw the damn diagram for this problem.
3. (Original post by djpailo)
Feel sorry for you. I can't even draw the damn diagram for this problem.
thanks for the solidarity. much appreciated.
4. (Original post by StarvingAutist)

this is my working: http://imgur.com/EbI2aXE

i'm not sure where i'm going wrong, or how to do the question as it specified.
Are you sure it's ? I keep getting , but maybe I'm just tired.
5. (Original post by morgan8002)
Are you sure it's ? I keep getting , but maybe I'm just tired.
well, that's what it says. could be wrong, i suppose. what's your method?
6. I got it!!!!!!! God damn
7. (Original post by StarvingAutist)
well, that's what it says. could be wrong, i suppose. what's your method?
I just applied conservation of energy and conservation of angular momentum like it says(set the total system energy and angular momentum to some constants), and I got the equation they say, but with r instead of r^2 like I said.
I'll check it again tomorrow.
8. I thought it was impossible, i was just about to give up, but then.... ah im so high right now
Spoiler:
Show
9. (Original post by morgan8002)
I just applied conservation of energy and conservation of angular momentum like it says(set the total system energy and angular momentum to some constants), and I got the equation they say, but with r instead of r^2 like I said.
I'll check it again tomorrow.
(Original post by EricPiphany)
I thought it was impossible, i was just about to give up, but then.... ah im so high right now
Spoiler:
Show
ah okay, i think i see now.
btw just stumbled upon this exact problem in the lecture notes... i suppose this is why i should go to lecures
10. (Original post by StarvingAutist)
ah okay, i think i see now.
btw just stumbled upon this exact problem in the lecture notes... i suppose this is why i should go to lecures
11. (Original post by StarvingAutist)

this is my working: http://imgur.com/EbI2aXE

i'm not sure where i'm going wrong, or how to do the question as it specified.
12. (Original post by atsruser)
I don't think so; Lagrangians hadn't been covered at the time
13. (Original post by StarvingAutist)
I don't think so; Lagrangians hadn't been covered at the time
OK. It looks like the kind of question that's easier with Lagrangians, though.

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