Two \(0.0450-\mathrm{kg}\) spheres are identical (including the charge they carry) and are initially pinned in place \(200 \mathrm{~mm}\) apart. You unpin them and push on each sphere with a force of \(0.15 \mathrm{~N}\). After their separation increases to \(400 \mathrm{~mm}\), each sphere has a speed of \(500 \mathrm{~mm} / \mathrm{s}\). What is the charge on each sphere? Is there more than one possible answer?