Calculating Forces on Charged Particles Using Vector Components

[inconceivable]

1. Find in the i, j, k format, the force on the +8 micro-Coulomb charge (pic att'd)

F = 1.6 x 10^-4 Nno clue where to start

thx

 

[Delphi51]

Use the formula for electric field causing a force on a charge: Fe = q*E

 

[inconceivable]

got that. that's where the 1.6 x 10^-4 came from.

 

[Delphi51]

Are you finished then, or do you need to add the electric field due to the other charge? A good idea to show formula and numbers - the answer is not much of a clue as to what you have done.

 

[inconceivable]

electric field strength is on the image - 20 N/C

the issue here is, they want it in i, j k format

 

[Delphi51]

Okay.
1.6 x 10^-4 * cos(60) i + 1.6 x 10^-4 * sin(60) j + 0k

 

[inconceivable]

thanks delphi. can you explain the cos and sin portion a bit? i never really could understand why those are used to express a single side of a triangle

 

[Delphi51]

Expressing a vector as a horizontal part plus a vertical part makes it very convenient to add vectors (just add the h and v parts separately without worrying about angles). Also, in something like a trajectory problem the motion in two perpendicular directions is independent, so you can do the horizontal part of the problem without worrying about the vertical part.