The beer corkscrew uses the principle of leverage, so where is its power point, the fulcrum, and the

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Lever principle: When using leverage, in order to save effort, the power arm should be used.

levers that are longer than the resistance arm; If you want to save distance, you should use a lever that is shorter than the resistance arm. Therefore, the use of levers can save effort and distance. However, if you want to save effort, you must move more distance; If you want to move less distance, you have to work harder.

It is impossible to achieve it with less effort and less distance.

It is from these axioms, on the basis of the theory of the "center of gravity", that Archimedes.

The principle of levers was discovered, that is, "when the duo is balanced, their distance from the fulcrum is inversely proportional to their weight." Archimedes' study of levers was not only theoretical, but also led to a series of inventions based on this principle.

Archimedes once said, "Give me a fulcrum and a lever long enough, and I can pry the earth." That's what we're talking about.

But you can't find that long and strong lever, and you can't find that foothold and fulcrum. So prying the earth is just an assumption of Archimedes.

The fulcrum of the lever does not have to be in the middle, and the system that satisfies the following three points is basically the lever: the fulcrum, the force point, and the force point. The formula reads:

Distance from the fulcrum to the force point (moment) * Force = Distance from the fulcrum to the force application point (force arm) * Force application, so it is a lever.

There are also labor-saving levers for leverage.

With strenuous leverage, both are available but have different functions. For example, there is a pump that is stepped on by the feet, or a juicer that is pressed by the hand, which is a labor-saving lever (force arm > torque); But we have to press down a large distance, and there is only a small movement on the stressed end.

There is also a laborious lever. For example, the crane on the side of the road, the hook for fishing things is at the tip of the whole rod, the tail end is the fulcrum, and the middle is the hydraulic press (torque > force arm), which is the laborious lever, but the laborious exchange is that as long as the middle force point moves a small distance, the hook at the tip will move a considerable distance.

Both levers are useful, but where they need to be used to evaluate whether they need to save effort or range of motion. There's another thing called an axle.

It can also be used as a leverage, but the performance may sometimes have to be added to the rotation calculation.

When levers are used, if the lever is stationary or rotates at a constant speed around the fulcrum, then the lever is in equilibrium.

Power arm power = resistance arm resistance, i.e., l1 f1 = l2 f2, which can evolve into the balance of f1 f2 = l2 l1 lever.

It is not only related to the dynamic force and resistance, but also to the point of action of the force and the direction in which it is acted.

If the power arm is n times that of the resistance arm, then the power is 1 n of the resistance"Big head sinks"

The longer the power arm, the less effort, and the longer the resistance arm, the more laborious.

Labor-saving leverage fee distance; Laborious lever saves distance.

The equal-arm lever is neither labor-saving nor labor-intensive. It can be used for weighing. For example: balances.

In many cases, the lever is tilted to rest because the lever is subjected to several equalizing forces.

role.

The power point is where the hand holds, the fulcrum is where it comes into contact with the edge of the cap, and the resistance point is also on the cap.

a. To open the cap, to overcome the friction between the cap and the mouth of the bottle, the resistance of the cap to the driver is downward, which does not meet the topic

b. The resistance of the bottle cap to the driver is downward, and the power and resistance make the clockwise rotation around the fulcrum o not in line with the topic

c. The resistance of the bottle cap to the screwdriver is downward, and the power is that the screwdriver rotates counterclockwise around the fulcrum o, and the resistance rotates clockwise around the fulcrum o in line with the topic

When we use the bottle lifter, it is to save effort, and in the process of use, the power arm is larger than the resistance arm, so it is a labor-saving lever;

When the bottle lifter in the figure opens the cap, the resistance acts at point B, and the bottle lifter rotates around point A, so point A is the fulcrum;

In the figure, the resistance arm is certain, and the force arm acting at point D is longer than the force arm acting on point C According to the equilibrium condition of the lever, it can be seen that the longer the power arm, the more labor-saving, so the force at point D is smaller than that at point C in the figure

So the answer is: labor-saving; a；d．

The fulcrum of is a; If the cap is opened forcefully in the vertical direction, the force at point d in the figure is minimal (2) As shown in the picture, the portable scale used in the store, its working principle is the same as that of the balance, which is made according to the principle of levers, but the length of the two arms is not equal

Before using the portable scale to weigh the object, it is also necessary to zero it, first place the code at the zero line, and then adjust the balance nut to make the scale rod balanced

Therefore, the answer is: (1) labor-saving; a；d．

2) leverage; Balance nut

<> pliers are held by hand, so the two handles are considered relatively fixed and the whole pliers are treated as a whole.

The contact point between the upper part of the tongs and the upper part of the cap is the fulcrum.

The lower part of the mouth and the point of contact with the fold of the cap are the points of resistance.

The pliers handle is a force point.

a. To open the cap, to overcome the friction between the cap and the mouth of the bottle, the resistance of the cap to the driver is downward, which does not meet the topic

b. The resistance of the bottle cap to the driver is downward, and the power and resistance make the clockwise rotation around the fulcrum o not in line with the topic

c. The resistance of the bottle cap to the screwdriver is downward, and the power is that the screwdriver rotates counterclockwise around the fulcrum o, and the resistance rotates clockwise around the fulcrum o in line with the topic

When the bottle lifter in the figure opens the cap, the resistance acts at point B, and the bottle lifter rotates around point A, so point A is the fulcrum;

When we use the bottle lifter, it is to save effort, and in the process of use, the power arm is larger than the resistance arm, so it is a labor-saving lever

In the figure, the resistance arm is certain, and the force arm acting at point D is longer than the force arm acting on point C According to the equilibrium condition of the lever, it can be seen that the longer the power arm, the more labor-saving, so the force at point D is smaller than that at point C in the figure

So the answer is: labor-saving; a；The labor-saving department weighs the lever, and the longer the power arm, the more labor-saving

1) When the bottle lifter in the figure opens the bottle cap, the resistance of the nuclear faction Hu Gai block acts on point B, and the bottle lifter rotates around point A, so point A is the fulcrum We use the bottle lifter in order to save effort, and in the process of use, the power arm is greater than the resistance arm, so it is a labor-saving lever In the figure, the resistance arm is certain, and the force arm acting on point D is longer than the force arm acting on point C According to the balance condition of the lever, it can be known that the longer the power arm, the more envious the envy force, so the force at point D is smaller than the force at point C in the figure

2) It is known that the resistance arm of the lever is 4 times that of the power arm, so this is a laborious lever;

The equilibrium condition formula by lever f1l1f2

L2 deformation can be seen: F1FL

l20n×4

80n；So the answer is: labor-saving; a；d；Laborious; 80．