Superpositions of electrostatic forces

AI Thread Summary
The discussion revolves around solving for the unknown charges of particles P2 and P3, given that three particles exert no net force on a charged particle at the origin. The user struggles with deriving the equations needed to find these charges, despite attempting various methods. They reference the use of electrostatic force equations and angles to set up their calculations but continue to encounter unresolved variables. A hint is provided to relate the forces acting on the particle at the origin, emphasizing the need to balance horizontal and vertical components. The user seeks clarification and assistance in resolving their calculations to determine the correct values for the unknown charges.
raindrops
Messages
16
Reaction score
0

Homework Statement



Three particles P1, P2, and P3 are located at the points (−2.00, −1.00), (0, 2.00), and (3.00, −1.00), respectively. P1 has a charge of 5.00 μC, but the charges of P2 and P3 are unknown. However, the three particles exert no net force on a charged particle that is placed at the origin. You are asked to find the unknown charges. (a) Use the fact that the net horizontal force on the particle at the origin is zero to find the unknown charge on P3. (b) Then use the fact that the net vertical force on the particle at the origin is zero to find the unknown charge on P2.

Homework Equations



Fnet = (Kq1q2)r2

K = 9*109

The Attempt at a Solution



I am at a loss on where to go with this one. I have tried about 10 different things but keep getting stuck with unsolved variables.

I also attached a drawing i did with some numbers for angles and such that i came up with.

Any help would be greatly appreciated!
 

Attachments

  • phys.png
    phys.png
    2.3 KB · Views: 506
Physics news on Phys.org
From the given hint you can write
K*Q*Q1*cosθ1/(d1)^2 =k*Q* Q3*cosθ3/(d3)^2. where q is the charge at the center.You have already found θ1 and θ3. So find Q3.
Similarly
kQ*Q2/(d2)^2 =K*Q*Q1*sinθ1/(d1)^2 + k*Q* Q3*sinθ3/(d3)^2. Find Q2.
 
This is one of the methods I used and I kept coming up with 9*10-6 which is wrong so, I don't know what to do. Maybe my math is wrong.

([STRIKE]K[/STRIKE] (5*10-6) [STRIKE]Q0[/STRIKE] cos (26.56)) / (2.23)2 = ([STRIKE]K [/STRIKE]Q3 [STRIKE]Q0[/STRIKE] cos(18.43)) / (3.16)2
 
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...
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...
Back
Top