Figure a is shown is a schematic diagram of the use of spike spike in railway construction to pry pry. Please draw the power of F1 arm L1 in the figure; standing on the ground who want to use a small force lifting. Please draw the winding pulley rope in Figure B.
According to the analysis of labor-saving pulley block of the hanging sections of movable pulley rope determines its effort, so the easiest to start when the driven pulley connection, and also note the final direction of pull.
Along the direction of force F1 vertical, down, along the long acting line, from the fulcrum O to draw a vertical line, the length of this vertical line is the power of the F1 arm L1, as shown;The hook of the driven pulley, to bypass the lower end of the fixed pulley, then down around the movable pulley, finally to the upper end of the sliding around, finally by three strings bear weight, people can stand with minimal force lifting heavy objects on the ground, as shown in the figure.
The lever arm of a lever is the distance from the fulcrum to the line of force, therefore, the fulcrum is determined, and the line of action of the force is drawn, and then the vertical line can be made;
