# Thread: Physics homework help (12U)

1. ## Physics homework help (12U)

A 700 g weight is held on a steel cable and spun in a vertical circle. If the cable can withstand a tension of 4100 N, at what velocity will the cable break. (Hint the tension is not the same throughout the period of rotation?
EDIT: I'm really sorry if this is the wrong section! Just send me a warning and I promise I'll watch myself next time!

2. Way to use us for the wrong section...
And we'd probably just give you the wrong answers.

3. ## The Following User Says Thank You to Kevin For This Useful Post:

ZigZak (03-19-2013)

4. Originally Posted by ZigZak
A 700 g weight is held on a steel cable and spun in a vertical circle. If the cable can withstand a tension of 4100 N, at what velocity will the cable break. (Hint the tension is not the same throughout the period of rotation?
EDIT: I'm really sorry if this is the wrong section! Just send me a warning and I promise I'll watch myself next time!
It would be helpful to state relevant equations you've learned in class if you want some help. Usually looking at these equations and their constituents will usually help you figure out what to use to solve the problem.

5. ## The Following User Says Thank You to iverson954360 For This Useful Post:

ZigZak (03-19-2013)

6. @iverson954360
I found this question somewhere else just now, but the thing is, you need radius to calculate this... And where I found the answer it says to assume the radius is 1m.

7. Originally Posted by ZigZak
@iverson954360
I found this question somewhere else just now, but the thing is, you need radius to calculate this... And where I found the answer it says to assume the radius is 1m.
You can try typing it into yahoo answers always helped me

8. Originally Posted by ZigZak
@iverson954360
I found this question somewhere else just now, but the thing is, you need radius to calculate this... And where I found the answer it says to assume the radius is 1m.
You probably want to use centripetal force equations to calculate this problem.

9. You need to give us the radius or the tension in order for me to solve this equation aff

10. Originally Posted by The Force
You need to give us the radius or the tension in order for me to solve this equation aff
You set the force equal to the critical tension given and as he said if he has to assume a radius of 1m he would have all he needs to solve for velocity.

11. Originally Posted by iverson954360

You set the force equal to the critical tension given and as he said if he has to assume a radius of 1m he would have all he needs to solve for velocity.
Ivy to the rescue

Originally Posted by ZigZak
A 700 g weight is held on a steel cable and spun in a vertical circle. If the cable can withstand a tension of 4100 N, at what velocity will the cable break. (Hint the tension is not the same throughout the period of rotation?
EDIT: I'm really sorry if this is the wrong section! Just send me a warning and I promise I'll watch myself next time!
Well then little kid /aff You're lucky I don't feel like doing my political cartoon aff

According to the centripetal force formula

Fc (subscript c) = mv^2 / 2

Fnet (subscript net) = ma, which is equal to Ft (tension subscript) - Fg (gravity subscript).

This will give you 4100 - (0.700)(9.81) = mv^2 / r = (0.700)v^2 (We use 4100 because tension is greater bottom of the rotation and less on the top)(We will use the 4100 on the top because the rotation is vertical. The top part is according to the gravity, and the bottom is going against it)

This will get you 4093.133 = 0.7v^2

4093.11 / 0.7 = 5847.33

Squareroot that and you get 76.47 rounded to the tenth.

Now in your original question the lowest significant digit is 1, so it would become 8*10^1

12. ## The Following 2 Users Say Thank You to KingDot For This Useful Post:

HalfBajan (03-20-2013),ZigZak (03-20-2013)

13. ALL THIS KNOWLEDGEEEEEEEEEE

14. Originally Posted by HuxJr
ALL THIS KNOWLEDGEEEEEEEEEE
Nigga didn't even thank me aff.

Never helping some kiddie with hw again aff

15. ## The Following User Says Thank You to KingDot For This Useful Post:

ZigZak (03-20-2013)

16. We need extra information, we can't work it out from 1 set of results, this case (N), we need radius.

17. Usually looking at these equations and their constituents will usually help you figure out what to use to solve the problem.

18. Originally Posted by The Force

Nigga didn't even thank me aff.

Never helping some kiddie with hw again aff
Well thanks this time! Can't wait to be done with school...

19. Originally Posted by iverson954360

It would be helpful to state relevant equations you've learned in class if you want some help. Usually looking at these equations and their constituents will usually help you figure out what to use to solve the problem.
Are you Asian?
You're fucking smart
(even though I don't know your year level)

Page 1 of 3 123 Last