Which rotation speed is not a typical spindle rotation speed for magnetic hard drives? 3100; 5400; 7200; 1

5,400 because it turns at the right speed, but if it is too fast or too slow, it will not perform at it's fullest potential. Such as speed and storage.

these  signals travel  down a part of the neuron called the axon, which is like a wire that carries the  signal  to othernerve  cells. on average a  nerve  cell sends a  signal  at about 50 meters per second, which is over 100  miles  an hour!