# Physics problem - Spring Constant

1. Jun 4, 2008

### allyson6018

Two spheres are mounted on two different identical horizontal springs and rest on a frictionless table (one spring is connected to the left side of a wall with a sphere attached to the other end & the other sphere is connected to the other spring which is connected to the other wall -- both spheres are facing each other) When the spheres are uncharged, the spacing between them is .05m, and the springs are unstrained. When each sphere has a charge of +1.60 uC, the spacing doubles (springs compress). Assuming that the spheres have a negligible diameter, determine the spring constant of the springs.

Okay so I know F= -kx, F=k [((q1)(q2)) / r^2] but I am not quite sure how to connect the dots....and what would q1 and q2 be??? Im confused....

2. Jun 4, 2008

### Staff: Mentor

The charge on each sphere is given. How much does each spring compress?

3. Jun 4, 2008

### MarkusNaslund19

q1 and q2 are the charges of the spheres, which is +1.60 micro C. r is the distance between the charges, which is double the original spacing between the spheres. Keep in mind that the two k's you have written in the equations above are not the same!

Anyways, you have the force F exerted onto the spheres (from F = (kq1q2)/r^2). Using F = -k_spring x, you can find the spring constant. All you need is x, which is the amount of compression.

Last edited: Jun 4, 2008