牛津第1,2,3定律是什麼?

牛頓吧..
牛頓運動定律是伊薩克·牛頓提出了物理學的三個運動定律的總稱，被譽為是經典物理學的基礎。

牛頓第一運動定律：當物體不受外力作用，或所受合力為零時，原先靜止者恆靜止，原先運動者恆沿着直線作等速度運動。這定律又稱為「慣性定律」。

牛頓第二運動定律：物體受力後其動量變化率，和其所受的淨力（即合力）成正比，及處於同一方向。

牛頓第三運動定律：當兩物體交互作用時，彼此互以力作用於對方，兩者大小相等，方向相反，但作用在不同的物作用體上。這定律又稱為「作用與反作用定律」。

Newton's laws of motion(1670s)

Newton's first law: If an object is at rest, or if its speed and direction are constant, then the resultant force on it is zero(Force on the object below are equal-no resultant force, so no acceleration.

Newton's second law: If the momentum of an object changes, eg. if it accelerates, then there must be resultant force acting on it. Normally, the mass of the object is constant, and the force is thus proportional to the acceleration of the object. The direction of the acceleration is the same as the direction of the force.
(Formula: F=ma F=Force, M=mass, a=acceleration)

Newtons third law: Forces always occur in equal and opposite pairs called the *action and *reaction. Thus if object A exerts a force on object B, object B exerts an equal but opposite force on A. These forces *do not cancel each other out, as they act on different objects.

Hope this would be useful for you :-)

2008-12-31 19:39:15 補充：
Example for Newton's third law:

Bat exerts force on ball, accelerating it in opposite direction.
Ball exerts equal and opposite force on bad(felt as sudden slowing down of bat)