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
Messages
28
Reaction score
0

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]
 
Last edited by a moderator:
Physics news on Phys.org
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:

Thread 'Errors and significant figures'

I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
View full post »
Thread 'A cylinder connected to a hanging mass'

Thread 'A cylinder connected to a hanging mass'

Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
View full post »

Similar threads

Finding tension in string in vertical circle
Replies
1
Views
2K
What actually is the centripetal acceleration formula?
Replies
28
Views
3K
Circular Motion Problem: Particle Velocity and Acceleration Calculation
Replies
18
Views
2K
Vertical circular motion in container
Replies
46
Views
6K
Normal forces for small car performing a vertical loop
Replies
4
Views
2K
Circular Motion With Constant Angular Acceleration
Replies
3
Views
2K
Circular motion grade 12 physics
Replies
4
Views
2K
Circular Motion -- Swinging keys on a string in a vertical circle
Replies
6
Views
4K
Circular Motion and Energy Calculations
Replies
11
Views
6K
What Forces Act on a Train Engine Going Around a Circular Curve?
Replies
10
Views
3K

Hot Threads

Recent Insights

Back
Top