Question

12) Two identical particles of charge 6 μC and mass 4 μg are initially at rest and held 4 cm apart. How fast will the particles move when they are allowed to repel and separate to very large (essentially infinite) distance? Answer: Last Answer

Hint: The particles are identical, so you can assume that the scenario is symmetrical. Use energy conservation: What type of energy is stored in the system when the particles are near each other and at rest? How does the voltage of a particle allow you to compute this energy? What about when the particles have flown away from each other? What is the relationship between these energies, according to energy conservation? (Also, remember that the SI unit for mass is the *kilo*gram and you are given the particle masses in *micro*grams.)

Now suppose that the two particles have the same charges from the previous problem, but their masses are different. One particle has mass 4 μg as before, but the other one is heavier, with a mass of 28 μg. Their initial separation is the same as before. How fast are the particles moving when they are very far apart? [Enter the heavier particle's final speed in the first box and the lighter particle's final speed in the second box.]

Answer 1 of 2:

Answer 2 of 2:

Hint: Notice that the asymmetry in the particle masses means that you cannot assume that they end up with the same speeds after separating. Use momentum conservation to help solve this problem.

Answer 1