Newton's force and circular acceleration

AI Thread Summary
The discussion centers on calculating the tension in a watch chain when swung in a vertical circle at a specific angle. The user initially calculated the tension as 1.765 Newtons but received feedback that this was incorrect. Suggestions included checking significant figures, with a recommendation to round the answer to 1.8 N. Another participant confirmed the initial calculations were correct, prompting the user to consider consulting their professor for further clarification. The conversation emphasizes the importance of accuracy in calculations and the potential impact of significant figures on grading.
homo-sapiens
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Homework Statement



Your niece finds her father's watch. The light watch chain has a length of 35 cm, and the mass of the watch is 190 g. Your niece swings the watch in a vertical circle, maintaining the speed of the watch at 2.4 m/s. Find the tension in the chain when it makes an angle of 43° with respect to the vertical. (Assume the watch is closer to the top of the circle than the bottom. Also assume the radius of the circle is 35 cm.)

Homework Equations



F=ma
a=v^2/r

The Attempt at a Solution



I drew free body diagrams, balanced the forces and derived at an equation. The answer I got was 1.765 Newton which was incorrect. Can someone please tell me what mistake I made??

http://puu.sh/bMw81/df16b4f7f9.png [/B]
 
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your work looks good but watch significant figures. Try 1.8 N.
 
i am pretty sure, sig fig doesn't matter to the website, because i have submitted answers which definitely has wrong sig figs but is still marked correct. thanks for the advice though, need to be careful of sig figs on tests and exams.
 
homo-sapiens said:
i am pretty sure, sig fig doesn't matter to the website, because i have submitted answers which definitely has wrong sig figs but is still marked correct. thanks for the advice though, need to be careful of sig figs on tests and exams.
I think your answer is correct.I have checked the calculation too.
 
http://puu.sh/bMPIE/b03325effc.png
I guess I should check with my prof about it.
thanks for the reaffirmation
 
Last edited by a moderator:
homo-sapiens said:
http://puu.sh/bMPIE/b03325effc.png
I guess I should check with my prof about it.
thanks for the reaffirmation
You are welcome.
 
Last edited by a moderator:

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