Posted by **AfterLife** on Sunday, August 28, 2011 at 9:52pm.

Determine the magnitude and direction of the total electric force on the +q charge by the +Q and -Q charges respectively. it should express and algebraic expression using Q,q,x,d and fundamental constants.

-- I am trying to post a graph but it is not willing to so I will try to explain it --

Q+ is up on the y access ( x = 0 ) and Q- is down the y access ( x = 0 ) , both at equal distances d of the origin. q is to the right of the x access ( y = 0 ) at a distance x from the origin

So I am trying to solve it like this

Net Force = (Force of +Q on q) + ( Force of -Q on q)

using this equation for force (Kq1q2)/r^2

but then we need to find the components right ?

so I thought it is like this

Fnet = sqrt ( Fnet of x components )^2 + (Fnet of y component)^2

but then for the x components , the r in the equation should be x ,, and for the y components the r should be d

am I right ? I feel confused and I think I am wrong :S

- Physics -
**bobpursley**, Sunday, August 28, 2011 at 10:11pm
You are almost right, however, it is easier for me to break up the two forces into vertical and horizontal components.

well, first, the force on q from Q is kQq/distance^2 at some angle from the horizonal (arc tan d/x)

the horizontal force is

a) kqq/distanc^2*cosTheta

if you calculate the horizontal force component from -Q, it is the same but in a opposite direction, so the net horizontal force is ZERO.

Vertical forces:

vertical force from Q (top) is

kQq/distance^2 * sinTheta in the down direction

vertical force from -Q (bottom) is the same, and in the down direction.

so the net force is downward,

2kQq/(d^2+x^2) * sin (arctan d/x)

- Physics -
**AfterLife**, Sunday, August 28, 2011 at 10:12pm
Thank you very much :D

## Answer this Question

## Related Questions

Physics - The figure below shows two pint charges, each of -2Q, fixed on the y-...

Physics - Twelve identical point charges are equally spaced around the ...

physics- check - 1. three point charges, q1, q2, q3, lie along the x-axis at x...

physics - Two point charges, q1 and q2, are placed 0.30 m apart on the x-axis, ...

Physics - q1= 25 pC q2 = -75 pC A) calculate the magnitude of the electric force...

Physics - A)When point charges q1 = +1.5 ìC and q2 = +5.7 ìC are brought near ...

why doesn't anybody ever help me. - 1. three point charges, q1, q2, q3, lie ...

Physics - A beam of unknown charged particles passes at right angle to the ...

physics - Three positive point charges of q1 = 4.0 nC, q2 = 6.4 nC, and q3 = 1.5...

physics - The physics of electric field between two charges. What is the ...