Motion

Motion (physics)In physics, motion is a change in position of an object with respect to time and its reference point. Motion is typically described in terms of displacement, velocity, acceleration, and time. Motion is observed by attaching a frame of reference to a body and measuring its change in position relative to another reference frame.
A body which does not move is said to be at rest, motionless, immobile, stationary, or to have constant position. An object's motion cannot change unless it is acted upon by a force, as described by Newton's first law. An object's momentum is directly related to the object's mass and velocity, and the total momentum of all objects in a closed system   does not change with time, as described by the law of conservation of momentum.
As there is no absolute frame of reference, absolute motion cannot be determined. Thus, everything in the universe can be considered to be moving.
More generally, the term motion signifies a continuous change in the configuration of a physical system. For example, one can talk about motion of a wave or a quantum particle where the configuration consists of probabilities of occupying specific positions.
Contents1 Laws of Motion       * 1.1 Classical mechanics       * 1.2 Quantum mechanics   * 2 Kinematics       * 2.1 Planar motion       * 2.2 Spherical motion       * 2.3 Spatial motion   * 3 List of "imperceptible" human motions       * 3.1 Universe       * 3.2 Galaxy       * 3.3 Sun       * 3.4 Solar System       * 3.5 Earth       * 3.6 Continents       * 3.7 Internal body       * 3.8 Cells       * 3.9 Particles       * 3.10 Subatomic particles   * 4 Light   * 5 Types of motion |
Laws of MotionIn physics, motion in the universe is described through two sets of apparently contradictory laws of mechanics. Motions of all large scale and familiar objects in the universe (such as projectiles, planets, cells, and humans) are described by classical mechanics. Whereas the motion of very small atomic and sub-atomic...