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# Circular motion, range of values of T? watch

1. Part (a) was nice and neat, but I'm a little confused about part (b).

So I resolved towards the centre of the circle and used circular motion acceleration through Newton's 2nd Law to get T = 3mgsinθ - (2/3)mg, but I'm not sure where to go from here.

I feel like I should instinctively solve for θ when Tis zero, but I'm not sure, since that would just imply that it is zero.

TeeEm
2. (Original post by WarwickPhysicist)

Part (a) was nice and neat, but I'm a little confused about part (b).

So I resolved towards the centre of the circle and used circular motion acceleration through Newton's 2nd Law to get T = 3mgsinθ - (2/3)mg, but I'm not sure where to go from here.

I feel like I should instinctively solve for θ when Tis zero, but I'm not sure, since that would just imply that it is zero.

TeeEm
is this an EDEXCEL question ?
if it is please tell me the paper
3. (Original post by WarwickPhysicist)

Part (a) was nice and neat, but I'm a little confused about part (b).

So I resolved towards the centre of the circle and used circular motion acceleration through Newton's 2nd Law to get T = 3mgsinθ - (2/3)mg, but I'm not sure where to go from here.

I feel like I should instinctively solve for θ when Tis zero, but I'm not sure, since that would just imply that it is zero.

TeeEm
By equating tension to the centripetal force

I have

Which gives when and when

Hence
4. (Original post by Euclidean)
By equating tension to the centripetal force

I have

Which gives when and when

Hence

TeeEm does this look right to you?
I am way too busy to look at this ...
that is why I asked the OP to tell me the paper so I can post my own personal solution
5. (Original post by TeeEm)
I am way too busy to look at this ...
that is why I asked the OP to tell me the paper so I can post my own personal solution
january 2010 M3 edexcel
6. (Original post by WarwickPhysicist)
january 2010 M3 edexcel
My answer is very wrong (sorry ). This paper is on my to-do list now...
7. (Original post by WarwickPhysicist)
january 2010 M3 edexcel
8. (Original post by Euclidean)
My answer is very wrong (sorry ). This paper is on my to-do list now...
nah it wasn't that wrong, i just got 7/3 instead of 4/3 for the coefficient of mg, but apart from this question the rest of the paper was really nice
9. (Original post by WarwickPhysicist)
january 2010 M3 edexcel
10. (Original post by WarwickPhysicist)
nah it wasn't that wrong, i just got 7/3 instead of 4/3 for the coefficient of mg, but apart from this question the rest of the paper was really nice
I didn't account for the weight of the particle which should increase the tension
11. and thanks for your help everyone
12. (Original post by WarwickPhysicist)
and thanks for your help everyone
13. (Original post by TeeEm)
yeah it did, thanks a lot! very impressed with your presentation
14. (Original post by WarwickPhysicist)
yeah it did, thanks a lot! very impressed with your presentation
thanks

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