# Homework Help: Two uniformly charge spheres are firmly fastened

1. Oct 2, 2007

### Xaspire88

Two uniformly charge spheres are firmly fastened to and electrically insulated from frictionless pucks on an air table. The charge on sphere 2 is three time the charge on sphere 1. Which force diagram correctly shows the magnitude and direction of the electrostatic forces: Explain

< -----Charge 1 Charge 2 -->

is this not correct? what should it be?

2. Oct 2, 2007

### learningphysics

What options are you given? If the charge on one is 3 times the charge on the other... then the charges are the same sign... hence they repel. the force on one sphere is equal and opposite to the force on the other sphere.

3. Oct 2, 2007

### Xaspire88

1. Charge 1---> Charge 2--------->

2. <---Charge 1 Charge 2-------->

3. <--------Charge 1 Charge 2--->

4. <--------Charge 1 <---Charge 2

5. <---Charge 1 Charge 2--->

6. Charge 1 Charge 2--->

So the magnitude of the force on each one would be the same so it would be option 5

repel each other so the forces are in opposite directions.. and they act upon each other in equal but opposite directions so the magnitude would be the same. OK #5 then.

4. Oct 2, 2007

### learningphysics

yup. #5 looks right to me.