Electricity, force, and component form?

Question

Consider the four charges in Figure P25.46 http://i137.photobucket.com/albums/q208/infinitbelt/p25-46.gif , in which d = 3 cm, q = 4 nC, the +x-axis points to the right, and the +y-axis points up. What is the force on the 1 nC charge at the bottom? Give your answer in component form, using i and j for and , respectively.

I am confused as how to start such problems. Any ideas?


Thanks!

Any ideas?

Thanks!

Answer 1

One step at the time.
1.As you know the force between two charges is
F=k(Q1 Q2)/R^2
2.Determine the forces of each charge on the 1nC charge. As you know each force is a vector and has a magnitude and the direction.
3.Finally use supperposition and sum the forces.

Quick analysis:
The q-charges will cancel each other in the x-axis (the i - components=0)
They will generate a force downward and since it is two of them ...

2Fq=[2 k (q (1nC)/d^2]cos(45) downward or – j direction

F6= k (6nc (1nC)/d^2] upward or +j direction

Ft=F6-2Fq= k (6nc (1nC)/d^2] - [2 k (4nC (1nC)/d^2]cos(45)
Ft=(k/(3cm)^2)(6-2(4)cos(45)C^2 e-18)
Ft=k(6-4(sqrt(2)e-18 C^2)/9e-4m

Well just do the math

I hope it helps