科学六年级上册复习资料(国外英文资料).docVIP

科学六年级上册复习资料(国外英文资料) Print the article, print this, and close the window The sixth grade book review of Information Science Author: anonymous source: the original hits 1506 update: 2011-1-1 22:31:41 the input: wxt editor: wxt Review of information science and the sixth grade first volume unit 1, at work, can make us labor-saving or convenient device called machinery. Screwdriver, hammer, scissors, the mechanical structure is simple, also called simple machines. 2, like this simple mechanical lever is called a crowbar. It has three points. The position of force is called force, the position of resistance is called resistance point, and the lever is supported so that the lever can be called the fulcrum around the rotation. 3 when the lever scales, the number of hook codes on the left is multiplied by the number of squares, equal to the number of hook codes on the right, multiplied by the number of squares. 4, when the resistance point to the fulcrum of the distance is greater than the point of force to the fulcrum of the distance, the lever effort. When the resistance point to the fulcrum is equal to the distance from the point of force to the fulcrum, the lever is effortless and effortless. When the resistance point to the fulcrum is smaller than the distance from the point of force to the fulcrum, the lever is labor-saving. 5. Like a faucet, the wheel and shaft are fixed together. The machine that can rotate is called the axle. In the labor force to the axle wheel, wheel axle is more labor-saving; in axial force effort. 6, like a pulley on top of a flagpole, a pulley that is fixed in one position but does not move is called a fixed pulley. The fixed pulley can change the direction of force. A pulley that can be moved together with the weight is called a movable pulley, and the movable pulley can save labor. 7, the moving pulley and the fixed pulley are used together, and the pulley block is formed, and the pulley block can save labor and change the direction of forc