(1) used to pry pry spike of railroad track spike, O is the fulcrum, make power arm and a resistance arm in a map of it.(2) use the fixed pulley and the movable pulley in the drawing B to winding the pulley block, which can change the direction of the force(3) as shown in fig, A, B, C and D are four terminals, to connect the lights L1 and L2 in parallel, try to connect the relevant terminals
(1) the resistance action point is A, the vertical and downward force, that is, the resistance F2; over O points as the vertical line of the resistance line, that is, the resistance arm L2, as shown:(2) to change the direction of the force, then the downward force should start from the fixed pulley around
(3) starting from the current flowing through the power of the cathode, C to A, so as to make the current flowing through the light bulb, L2 L1 respectively then BD, together, this current will converge at another point, and finally back to the cathode of the power supply, so as to make the L1 and L2 in parallel.
1) to solve this problem, it is necessary to grasp the concept of the arm of an arm, and know that the arm is the distance from the fulcrum to the line of force. The vertical line is made by the line of action of the fulcrum to the force, and the length of the vertical line is the arm of an arm(2) the design principle of the pulley block can be summed up as follows: odd movement and even setting; moving with a certain, even less certain, variable to certainIf the current occurs at a point, shunt through the appliance on the branch, and then converge at another point, and then back to the negative pole of the power, this connection is called parallel
