For instance, the motion of a spacecraft, regarding its orbit and attitude , is described by the relativistic theory of classical mechanics, while the analogous movements of an atomic nucleus are described by quantum mechanics.
According to the NHS, the average Briton walks between 3,000 and 4,000 steps a day - significantly less than the Fitbit target. Yet many people do significantly more, and for them 10,000 steps might not be much of a target.
The goal of taking 10,000 steps in a day is a rough equivalent to the Surgeon General's recommendation to accumulate 30 minutes of activity most days of the week. It should be enough to reduce your risk for disease and help you lead a longer, healthier life.