What is the net force on the rectangular loop due to the straight wire?

[dangish]

A rectangular loop of wire, L = 23.6 cm and W = 11.6 cm, carries a I1 = 1.70 A current and lies in a plane (d = 12.8 cm), which also contains a very long straight wire carrying a I2 = 12.2 A current as shown in the figure below. (Follow the link)

http://capaserv.physics.mun.ca/giancoli-calc/Graphics/Graph28/dgian2850.gif

Calculate the net force on the loop due to the straight wire.



First off, I realize that there is only a force on the two wires that are parallel to each other.

I tried using F1 = u0*I(1)*I(2) / 2Pi*d

and F2 = u0*I(1)*I(2) / 2Pi*2d

Then adding them together to get the net force. I only have 2 tries left before I can no longer answer the equation, so I need a big kick in the right direction.

The Attempt at a Solution

 

[Dadface]

1.For F2 the distance is not 2d it is d+w
2.F1 is an attractive force and F2 a repulsive force so you need to subtract not add.

(like currents attract...unlike currents repel)

 

[dangish]

Thank you very much good sir

 

[dangish]

I still did not get the right answer.. This is what I did

F1 = u0*I(1)*I(2) / 2Pi*d , which came out to be 3.24x10^-5N
and
F2 = -u0*I(1)*I(2) / 2Pi*(d+w) , which came out to be -1.7x10^-5N

then I subtracted them to get 1.54x10^-5N, which is wrong

Anyone have some other hints? I only have one try left..

 

[Dadface]

Haven't checked your numbers but did they want you to give the direction of the force ie towards the wire?

 

[dangish]

Hard to say, I posted the whole question, it just says find the net force. If they just want magnitude I think adding them would be correct?

 

[Dadface]

Hello dangish,it looks like you calculated the force per unit length(per metre)on each of the parallel sides but the wires are not one metre long they are 0.236 metres long.