Two balls one made of aluminum and another made of steel are sitting at the bottom of some lake adjacent to each other. The radiuses of balls are the same. What ball experiences greater buoyancy force

The answer is 4f======since electrostatic force is given by    we let f be the electrostatic force when  r = 1 m    if we let  denote the electrostatic force when the distance is decreased so that r = 0.5m, then    we established earlier that f = kq₁q₂. therefore    the force will now be 4f.