What is the least leverage
I drew a random picture
1, how to make the lever arm should pay attention to the following questions:
first of all, we should find the position of fulcrum O and find an effortless route of action; Secondly, beyond the fulcrum o-force action line (forward or reverse, which may need to be extended), the length of this section is perpendicular to the arm of force
2, how to make the minimum force rod? I tell the students a new concept in the speech, in order to force it to be at least a fulcrum to the line of action of the force as a lever connection/& gt; Because the arm and the magnetic line of force are perpendicular to each other, the line of the past force point is perpendicular to the position of the arm, which is the minimum force/& gt; The next step is to determine the direction of the force. According to lie's direction, levers can be divided into two categories: one end is the fulcrum of the lever, and two forces on the same side of the fulcrum. When the rod or lever on the opposite side of the direction of the two forces revolves around the fulcrum (and the general physical mapping problem needs to balance the position of the rod), the other is the fulcrum of the middle lever (not necessarily in the middle), and the two forces on the opposite side of the upper fulcrum, The control rod or lever on the same side in the direction of the two forces rotates around the pivot point
so you can solve your second problem
in order to let you hear more clearly, I seem to be a bit wordy. I'm not here to give you the icon, just to give you theoretical knowledge. I just read my introction, and I promise you will be drawn. I hope I can solve your question in his heart! At the same time, I hope you make progress!
(1) Find out the fulcrum of the lever. When looking for the fulcrum, one must firmly grasp the characteristics of the fulcrum - the fixed point around which the lever rotates; Second, we should pay attention to the point around which the object can rotate; (2) find the maximum arm of force and determine the point of action of power: see which point on the lever has the largest distance from the fulcrum, and then connect the fulcrum with this point to get the maximum arm of force, Then this point is the minimum power
extended data:
lever balance
lever balance refers to the lever under the action of power and resistance in the state of static or uniform rotation
There are two kinds of forces on the lever:1. There are only two forces on the lever:
power × Distance from fulcrum to dynamic action line = resistance × The distance from the fulcrum to the resistance action line
is the dynamic force × Power arm = resistance × Resistance arm
is F1 × L1=F2 × L2
2. There are many forces on the lever:
the proct of the force that makes the lever rotate clockwise and its corresponding arm is equal to the proct of the force that makes the lever rotate counterclockwise and its corresponding arm
this is also known as the principle of leverage, which also applies to the case of only two forces
lever classification
lever can be divided into labor-saving lever, labor-saving lever and equal arm lever. No lever can save both distance and labor. These kinds of levers have the following characteristics:
labor-saving lever
L1 & gt; L2,F1< F2, labor saving and distance consuming
for example, claw hammer, guillotine, bottle opener, rolling knife, movable pulley, scissors for cutting iron sheet and steel bar, etc
leverage
L1 & lt; L2,F1> F2, effort and distance saving
such as fishing rod, tweezers, chopsticks, paddles, scissors for tailor, scissors for barber, etc
equal arm lever
L1 = L2, F1 = F2, which is neither labor-saving nor laborious, nor much moving distance,
such as balance, fixed pulley, etc
reference: network leverage principle
. The mass of the earth is about 6 × 1024
kg, and the thrust proced by human is about 588n. We assume that we want to pry up the earth and find a suitable fulcrum. According to the lever balance conditions, the ratio of the power arm and the resistance arm is 1023
: 1. Of course, it is very difficult to find such a long lever, But this imaginary experiment contains scientists' deep understanding of Physics: as long as the ratio of power arm to resistance arm is large enough, the ratio of power to resistance will be small enough, so the use of leverage will be the most labor-saving
O is the fulcrum, the power acts on the a end of the lever, and the connection of OA is the longest arm of force. Through a point, the force perpendicular to OA is made, and the direction is inclined upward, as shown in the figure:
(2) connecting the fulcrum and the farthest point, the line segment is the power arm
(3) make a straight line perpendicular to the line segment
(4) determine the direction of the minimum force.