A70 m wide river flows at 0.80 m/s [e]. a girl, starting on the south shore, swims across it at 1.4 m/s relative to the water.

a) what is the least time she requires to cross the river?

b) how far downstream will she be when she lands on the opposite shore?

c) at what angle to the shore would she have to aim, in order to arrive at a point directly opposite the starting point?

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