A motorcyclist started a race from START line and from rest, and accelerated with the acceleration of 2 m/s2 for 7 seconds. Then he increased the acceleration to 4 m/s2 and went with that acceleration for 8 seconds. What was the racer’s position from the START line after 7+8 seconds from the start of the race?

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