Homework Help: Find the y-compnent of the force

1. Oct 21, 2008

kdizzle711

1. The problem statement, all variables and given/known data
Object A, which has been charged to + 21.2nC , is at the origin. Object B, which has been charged to + 19.7nC , is at (x,y)= (0cm, 2.80cm) .

What is the y-component of the force (F a on b)y on B due to A

2. Relevant equations

F=K(q1)(q2)/(r^2)

3. The attempt at a solution

F= (9*10^9)*(21.2*10^-9)*(19.7*10^-9)/(.028^2)
= .0047N

Where am I messing up? Thanks

Last edited: Oct 21, 2008
2. Oct 21, 2008

LowlyPion

From your statement of the problem I get 4.8*10-3 N in the positive y direction.

Which is seemingly about the same as yours. Is there a preference for how the answer should be entered perhaps?

3. Oct 21, 2008

tiny-tim

Thanks, LowlyPion!

(though why does the question bother to ask for the y-component if everything's on the y-axis anyway? )

Last edited: Oct 21, 2008
4. Oct 21, 2008

LowlyPion

Edit: Agreed. The wording of the OP seems more designed to encourage careful reading than grasping the concepts. I suppose it is preparation for latter problem statements.

Last edited: Oct 22, 2008