Two people push on the same door from opposite sides as shown. A man pushes on a door from the left. A woman pushes on the door from the right. They will only see the door move when both people exert the same force so that the forces are unbalanced. neither person exerts a force on the door so that the net force is zero. one person exerts more force than the other so that the forces are unbalanced. both people exert the same force so that the forces are balanced.

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