An alpha particle (the nucleus of a helium atom, with charge +2e and a mass four times that of a proton) and an antiproton (which has the same mass as a proton but charge -e) are released from rest a great distance apart. They are oppositely charged, so each accelerates toward the other.
Hint: You'll need to use the two conservation laws. And what does "a great distance" suggest about the initial value of r?
A) What is the speed of the alpha particle when the particles are 1.4 nm apart?
B) What is the speed of the antiproton when the particles are 1.4 nm apart?