初三物理基本概念复习(2003.04.30)(国外英文资料).docVIP

初三物理基本概念复习(2003.04.30)(国外英文资料) This paper consists of a steady contribution Review of basic concepts of physics in junior middle school 2003.04.30 Mechanics, sound 1. Mechanical movement means that the motion and stillness of an object are. Geostationary satellites are relatively stationary, relatively moving. 2. The result of measurement consists of and consists of. As shown, the length of the object to be measured is cm, and the accurate value is cm. The difference is called error, and the commonly used method in experiments is to reduce the error. 3, called uniform linear motion. The physical meaning of the 6m/s representation is that Hop km/h. 90km/h= m/s. 4, a and B are 30 kilometers away from each other, the first half of the car with 10 m/s speed forward, the latter half with 15 m/s speed forward, then the entire average speed is m/s. 5. The sound comes from, the sound spreads the material. In a vacuum, the sound travels at m/s, and the sound travels at m/s at 15 degrees centigrade. 6, the three elements of music, and noise control should focus on,, The three link, in which the basic is to eliminate or reduce noise. 7, called quality, in the international system of units, the quality of the main unit is. In laboratory, the quality of an object is often referred to as a lever. 8 density is one of the properties of matter. The density of the same substance in the same state is, the density of matter and the object And unrelated. P = /m3 kg of water, the physical meaning is. 9, the principle of measuring the density of matter is. There are several steps to measure the density of a liquid. The correct procedure is (A) said the quality of M1 empty beaker (B) put the beaker liquid into the cylinder, the amount of liquid volume V1 (C) the amount of liquid into the empty beaker called total mass M2 (D) from a beaker pour liquid amount of liquid to the cylinder, the amount of the liquid volume of V2 (E) said that the total mass of the beaker and the remaining liquid i