牛顿三大定律:Newton's three basic principles

The first law describes a fundamental property of matter, called inertia, as follows:
Every body remains in a state of rest or in a state of uniform motion (constant speed in a straight line) unless it is compelled by impressed forces to change that state.


Newton's second law describes the manner in which a force compels a change of motion, at a rate of change called acceleration. It can be stated as follows:
Change of motion is proportional to the impressed force and takes place in the direction of the straight line in which that force is impressed.

Newton's third law may be stated as follows:
Action and reaction are equal and opposite.
This law is often expressed as “for every action there is an equal and opposite reaction.”

万有引力定律:Newton's Law of Gravity
Each object in the universe attracts each other body.