To practice Problem-Solving Strategy 25.1 for charge interaction problems. A proton and an alpha particle are momentarily at rest at a distance rrr from each other. They then begin to move apart. Find the speed of the proton by the time the distance between the proton and the alpha particle doubles. Both particles are positively charged. The charge and the mass of the proton are, respectively, eee and mmm. The charge and the mass of the alpha particle are, respectively, 2e2e and 4m4m.