| Excerpt |
|---|
Objects that have a changing velocity must be experiencing a forceNewton's First Law describes what happens in the absence of forces. If an object is moving with no force acting upon it, then it will move with constant velocity. Note that velocity is a vector, so this statement implies that the object will keep the same speed and the same direction of motion. This directly contradicts the animistic view of motion in which the natural condition of a body is at rest with respect to its surroundings - the First Law says the natural state of a body is moving with zero acceleration, not zero velocity. |
Page Contents | ||||
|---|---|---|---|---|
|
...
| Info |
|---|
If the First Law seems unnecessary to you, it is worth remembering that the possibility of the "action at a distance" of gravity (one of the central ideas of Newton's Principia) was by no means a commonly held belief in Newton's day. The First Law might be viewed as a statement that orbits must be explained by a force exerted by the central body, even if no " mediator " of such a force is observed. |