You arrange to meet a friend at 5: 00 p. m. on valentine’s day on the observation deck of the empire state building in new york city. you arrive right on time, but your friend is not there. she arrives 5 minutes late and says the reason is that time runs faster at the top of a tall building, so she is on time but you were early. is your friend right? does time run slower or faster at the top of a building, as compared with its base? is this a reasonable excuse for your friend arriving 5 minutes late?

An alpha particle with kinetic energy 12.5 mev makes a collision with lead nucleus, but it is not "aimed" at the center of the lead nucleus, and has an initial nonzero angular momentum (with respect to the stationary lead nucleus) of magnitude l = p0 b, where p0 is the magnitude of the initial momentum of the alpha particle and b=1.40×10−12 m. (assume that the lead nucleus remains stationary and that it may be treated as a point charge. the atomic number of lead is 82. the alpha particle is a helium nucleus, with atomic number 2.) what is the distance of closest approach?