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1. ### Intro Physics Books for high school physics E&M [No integrals]

I am mainly looking for some modern book with media links in the book.
2. ### Intro Physics Books for high school physics E&M [No integrals]

so you can't recommend to your students any English books?
3. ### Intro Physics Books for high school physics E&M [No integrals]

If you are a high-school teacher can't you recommend a few books?
4. ### Intro Physics Books for high school physics E&M [No integrals]

Is there a good "classic" book available?
5. ### Intro Physics Books for high school physics E&M [No integrals]

Can you recommend introductory physics book for high school that contains E & M ? It should not have any integrals.
6. ### [Electrical force] 2 balls hanging from ceiling, angled

1 - cos^2(10) + sin^2(10) = 2sin^10 because cos^2(10) + sin^2(10) = 1
7. ### [Electrical force] 2 balls hanging from ceiling, angled

I have checked this and I get r = 2a*sin10
8. ### [Electrical force] 2 balls hanging from ceiling, angled

I don't think I will need these advance techniques in my exercises
9. ### [Electrical force] 2 balls hanging from ceiling, angled

sqrt(4a^2sin^2(10)) = 2*a*sin10 How do you get from 1 - cos^2(10) - sin^2(10) to 2 sin^2(10) ?
10. ### [Electrical force] 2 balls hanging from ceiling, angled

I still don't see how this is correct as angle 10 is not adjacent to r
11. ### [Electrical force] 2 balls hanging from ceiling, angled

correct solution
12. ### [Electrical force] 2 balls hanging from ceiling, angled

It looks like the Tan approach was correct
13. ### [Electrical force] 2 balls hanging from ceiling, angled

When I changed the sign now result looks correct. I don't think you can get r in such a way because angle 10 degrees is not adjacent to r
14. ### [Electrical force] 2 balls hanging from ceiling, angled

This looks easy, but why was my attempt flawed with Tan10 ?
15. ### [Electrical force] 2 balls hanging from ceiling, angled

q*q/(4*PI*Eps0*r^2) = (m*g / Cos10) * Sin10 And then just move everything except q on the right side
16. ### [Electrical force] 2 balls hanging from ceiling, angled

Into the bottom equitation I can insert equation for T and get q which is the only unknown?
17. ### [Electrical force] 2 balls hanging from ceiling, angled

T = mg / Cos10 Fx = Fe = T*sin10
18. ### [Electrical force] 2 balls hanging from ceiling, angled

Fx/T = sin 10 -> Fx = Fe = T*sin10
19. ### [Electrical force] 2 balls hanging from ceiling, angled

this Fx - Fe = 0 Fx = (1/(4*PI*Eps0))*(q*q/r^2)
20. ### [Electrical force] 2 balls hanging from ceiling, angled

that is cosinus -> T = mg / Cos10
21. ### [Electrical force] 2 balls hanging from ceiling

I can paste the text in my native language but I don't know if it would help
22. ### [Electrical force] 2 balls hanging from ceiling, angled

Fe = Fx Fg = Fy Fx = (1/(4*PI*Eps0))*(q*q/r^2) Fy = mg
23. ### [Electrical force] 2 balls hanging from ceiling, angled

horizontal: Fx - Fe = 0 -> Fe = Fx vertical: Fg - Fy = 0 -> Fg = Fy
24. ### [Electrical force] 2 balls hanging from ceiling, angled

ok but neither the Tension nor Fe are known, and we need Fe ?

26. ### [Electrical force] Electrical charge in equilateral triangle

If you want to use Pythagorean theorem or Cos/Sin function you need one angle to be 90 degrees.
27. ### [Electrical force] Electrical charge in equilateral triangle

I have used for gamma = 60 and got correct result but how do you know that gamma = 60 ? I don't know why I thought that any of the angles is 90 degrees. The correct result:
28. ### [Electrical force] Electrical charge in equilateral triangle

Should I use the Law of cosines ? c^{2}=a^{2}+b^{2}-2ab*cos Then I would need angle gamma? I have updated the picture
29. ### [Electrical force] Electrical charge in equilateral triangle

I have used Cosines to calculate Fr and I still don't get the correct result:
30. ### [Electrical force] 2 balls hanging from ceiling

I am satisfied with easier route for this exercise.
31. ### [Electrical force] 2 balls hanging from ceiling

That is a very strange exercise with a lot of redundant information it seems
32. ### [Electrical force] 2 balls hanging from ceiling

Do I need to determine it to solve this exercise?
33. ### [Electrical force] 2 balls hanging from ceiling

but where is the electrical force and what about all the rest of information (mass, charge, distance)
34. ### [Electrical force] 2 balls hanging from ceiling

You mean like that? Fthread = Fceiling + Fbody = 0
35. ### [Electrical force] 2 balls hanging from ceiling

aha I understand that, but what is then acting on the threads?
36. ### [Electrical force] 2 balls hanging from ceiling

2 Electrical forces and 2 gravitational forces
37. ### [Electrical force] 2 balls hanging from ceiling

yes but we need to know the sum of all forces on all threads

40. ### [Electrical force] Electrical charge in equilateral triangle

I will check if forces are right-angled
41. ### [Electrical force] 2 balls hanging from ceiling

gravitational and electrical force
42. ### [Electrical force] 2 balls hanging from ceiling

I would say this is correct: Fthread = -Fg1 - Fg2 - Fe1 + Fe2 so 2 gravitational forces point down and 1 electrical force is pointing up
43. ### [Electrical force] 2 balls hanging from ceiling

I think that this is correct? Fthread = -Fg1 - Fg2 - Fe1 + Fe2
44. ### [Electrical force] 2 balls hanging from ceiling

As I understand the exercise there are 2 forces acting on these thread, gravitational and electrical. And the sum of both is suppose to be 0.
45. ### [Electrical force] 2 balls hanging from ceiling

Something like that? Fthread = Fg1 + Fg2 + Fe1 + Fe2
46. ### [Electrical force] 2 balls hanging from ceiling

I mean all the forces working on the thread combined. A sum of all the forces working on that thread. Which are only force of gravity and electrical force. And the sum of all those forces working on a thread should be 0. I have provided all the information from the book. I have translated the...
47. ### [Electrical force] Electrical charge in equilateral triangle

F23 is a force on the 3rd charge from 2nd charge F13 is a force on the 3rd charge from the 1st charge Fr is a sum of both (Pythagorean theorem).
48. ### [Electrical force] 2 balls hanging from ceiling

If the balls have both the same mass and charge They are both charged with the same charge as I already specified. No information about if they are the same weight. Assume they are both the same weight. Which thread tension you wish to found. The combine force in the thread.