41. Note : Here, speed means the time derivative of a displacement, not the speed of sound. 42. A common occurrence in physics is the time derivative of a vector, such as velocity or displacement. 43. The overdot on the " m " is Newton's notation for a time derivative . 44. :Ehrenfest's theorem gives you the time derivatives of the average of the position and momentum. 45. :For the first question : Newton's laws have no time derivatives higher than order 2. 46. The time derivative of the changing momentum of the object is what we label as " gravitational force ". 47. Time derivatives are denoted by dots, and are evaluated according to Hamilton's equations for the system.48. The time ordering is taken before the time derivatives inside the, " i " } }. 49. For high stress states / short time periods, the time derivative components of the stress strain relationship dominate. 50. These induced currents are proportional to the time derivative of the magnetic field, leading it by 90 degrees.
