3) An athlete swims the length of a 50-m pool in 20 s and makes the return trip to the starting position in 22 s. Determine her average velocities in (a) the first half of the swim, (b) the second half of the swim, and (c) the round trip.​

It may seem strange that the selected velocity does not depend on either the mass or the charge of the particle. (for example, would the velocity of a neutral particle be selected by passage through this device? ) the explanation of this is that the mass and the charge control the resolution of the device--particles with the wrong velocity will be accelerated away from the straight line and will not pass through the exit slit. if the acceleration depends strongly on the velocity, then particles with just slightly wrong velocities will feel a substantial transverse acceleration and will not exit the selector. because the acc