Chapter 2&3 Kinematics 2-1&3-6 Reference frames(参考系) and Displacement(位移)P17-18 The world, and everything in it, moves. Even seemingly stationary things, such as a house moves with the earth. the earth's orbit around the sun. the suns orbit around the center of the milky Way galaxy, and that galaxy's migration relative to other galaxies 绝对静止的物体是没有的运动的绝对性Chapter 2&3 Kinematics 2-1&3-6 Reference Frames （参考系） and Displacement（位移）P17-18 The world, and everything in it, moves. Even seemingly stationary things, such as a house moves with the Earth, the Earth’s orbit around the Sun, the Sun’s orbit around the center of the Milky Way galaxy, and that galaxy’s migration relative to other galaxies. 绝对静止的物体是没有的—— 运动的绝对性