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.
But on average we walk only about 4,000 steps a day. It takes about ten minutes to walk 1,500 steps. Professor Tudor Locke, an American academic specialising in physical activity, suggests that walking fewer than 5,000 steps a day indicates a sedentary lifestyle.