How Fast Do the Spheres Move When Far Apart?

[asheik234]

Homework Statement

k = 9 * 10^9

Sphere A of mass m = 0.0004 kg holds a positive charge qA = 3.0 10^-5 C and is fixed in place. Point P is d = 0.03 meters away from Sphere A.

Sphere B is identical in mass to sphere A, but carries a charge of qB = 3.6 10^-5 C. Sphere B is brought from a distant location and fixed at point P.

If both spheres are released from rest at the same time, how fast do the spheres move when they are very far apart?

Homework Equations

KE = (1/2)mv^2
KE = qV

The Attempt at a Solution

I keep getting different speeds for each ball using the first equation, any help would be appreciated.

 

[haruspex]

Pls post your working, as per forum rules.

 

[asheik234]

Pls post your working, as per forum rules.

I'm not sure if I have to get the velocity of ball a or ball b, or get them both and average, I just need help on this part of the problem.

 

[asheik234]

Pls post your working, as per forum rules.

I'm not sure if I have to get the velocity of ball a or ball b, or get them both and average, I just need help on this part of the problem.

 

[haruspex]

I'm not sure if I have to get the velocity of ball a or ball b, or get them both and average, I just need help on this part of the problem.

They're the same mass. What does conservation of momentum tell you about the relationship between their velocities?