Is it true that complex machines are machines?

Wrong. Machinery is a general term for mechanisms and machines. Mechanisms and machines range from simple to complex. The lathe is more complicated, but the single bike is simple.

This statement is certainly not true, and complex machinery is not necessarily a machine.

Complex machinery can be mechanical.

A machine is a combination of complex machinery that represents.

It is not true to say that a complex machine is a machine, which is a device assembled from various metal and non-metal parts, which consumes energy and can operate and do work.

It is used to replace human labor, to transform energy, to process information, and to produce useful work.

Complex machinery is a machine, I don't think that's true, because well, complex machinery is not necessarily a machine, but a machine can be a complex machine.

Why is it normal to say that machines are machines? I don't think it's right, some simple machines are also machines.

Thanks, is that what the machine says? I feel that complex machines are not machines, and this statement is not true.

Inaccurately, a machine is a type of machinery, but a complex machine does not mean that it is a machine.

The machine I'm holding is the machine, and besides, I feel that this very normal thing is very important, very good.

Is it true that complex machinery is machinery? Complex machines are machines, and this approach is right.

Complex machinery is everything about machinery. Is this true? I think it's true that complex machines are machines.

Complex machines, the words of the machine are still very good, pushing you to the rearguard.

Whether it is a complex machine or a simple machine, it is actually called a machine, but the machine is divided into two types: intelligent and non-intelligent.

Hello, complex machinery is a machine, I don't think there's anything wrong with this sentence, and it's quite correct, thank you.

What a machine is a machine, this statement is true.

Complex set solution, he is a configuration formed by many parts of the assembly.

Solution: (1) The use of fixed pulley does not save effort, but it can change the direction of force;

2) The inclined plane is also a simple machine, which saves effort but consumes distance when using the inclined plane; When the height of the inclined plane is the same, the longer the more labor-saving;

3) The use of movable pulleys can save half of the force, but it cannot change the direction of the force;

4) The pulley block can change the magnitude of the force, and can also change the direction of the force, or it can change the magnitude of the force and the direction of the force;According to the principle of work, the work-saving machinery is the wheel that does not exist

a, the essence of the fixed pulley is that the power arm is equal to the resistance arm is equal to the arm lever, so a is wrong;

B, the use of inclined plane can save effort, when the slope height is the same, the longer the inclined plane is more labor-saving, so B error;

c. The movable pulley is essentially a lever with a power arm twice as much as the resistance arm, and the use of the movable pulley saves effort but cannot change the direction of the forceTherefore, the noisy field clear the ridge c wrong;

D, the pulley block in the use of both labor-saving and can change the direction of force, so D is correct so choose D 2, about simple machinery, the following statement is correct ( ) a fixed pulley is a power arm is 2 times the resistance arm of the labor-saving lever b lifting the front inclined plane is a laborious machinery.

c The direction of the force can be changed by using a movable pulley.

d The use of pulley blocks can not only save labor, but also change the direction of force.

The machine has the following three characteristics:

1. Man-made physical combinations.

2. Each part has a definite relative motion.

3. Replace or alleviate human labor, complete useful work or realize the conversion of energyUsually a complete machine consists of three basic parts:

1) The motivation part: its function is to convert other forms of energy into mechanical energy (such as internal combustion engines and electric motors convert thermal energy and electrical energy into mechanical energy, respectively). The prime mover part is the power source that drives the entire machine to complete the predetermined function.

2) Working part (or execution part): its function is to use mechanical energy to convert or transmit energy, materials, and signals, such as generators to convert mechanical energy into electrical energy, rolling mills to transform the shape of materials, and so on.

3) Transmission part: its function is to transform the motion form, motion and power parameters of the prime mover into the motion form, motion and power parameters required by the working part.

Whether the object has kinetic energy, or pure gravitational potential energy or elastic potential energy, the branches are all mechanical energy, so it can be said that the object has mechanical energy and slip.

When the object has both kinetic energy and potential energy, the object also has mechanical energy but it cannot be said that only this case has mechanical energy

Therefore, choose D

Answer: B: Use a movable pulley and a fixed collapsing companion pulley to save the most effort of the groupThe use of fixed pulleys can not save force, but it can change the direction of force;The use of movable pulleys can save effort, but not the front brigade can save distance;The use of pulley block can save effort, but not distance, so choose B

Answer C analysis: (1) The use of inclined planes can save effort;

2) The essence of the fixed pulley is the equal arm lever, which can not save force, but can change the direction of force;

3) Combined with life experience, judge the relationship between the size of the power arm and the resistance arm in the process of using the balance, and then judge what type of lever it belongs to.

4) The essence of the movable pulley is that the power arm is twice the lever of the resistance arm, which can save half of the force, but it cannot send orange Qing to change the direction of the force

Answer: a, the use of inclined planes can save effort, so a is wrong;

B, the use of fixed pulley can not save force but can change the direction of force, so B is wrong;

c. In the process of using the balance dust, the power arm is equal to the resistance arm, which is the equal arm lever, so C is correct;

D. The use of movable pulleys can save half of the force, but it cannot change the direction of the force, so D is wrong Therefore, choose C Comments: Most of the content examined in this question is memorization, which is relatively simple and not difficult to solve

Answer D analysis: mechanical efficiency refers to the proportion of useful work to total work, the speed of work done by objects is compared with power, and the amount of work done is related to power and time; There is little relationship between mechanical efficiency and power

Answer: a, from the formula w=pt, the amount of work done by the free body is proportional to the power and time, the power is larger, the time is uncertain, and the amount of work done cannot be determined This option is wrong;

b. High mechanical efficiency, which means that the useful work imitates a large proportion of the total work, and the amount of work done cannot affect the mechanical efficiency This option is wrong;

c. Whether the machinery is labor-saving is related to the type of machinery and the method of use, and has nothing to do with the efficiency of the machinery This option is wrong;

d. Power describes the speed of work done by the object, the faster the work done by the object, the greater the power This option is correct

Therefore, choose D Comment: This question tests students' understanding of mechanical efficiency, especially noting that power and mechanical efficiency are two different physical sales, and there is no relationship between them

Answer A analysis: mechanical efficiency is the ratio of useful work to total work Total work is the sum of useful work and extra work, and when using a pulley block, the work done to overcome the gravity of the moving pulley is the extra work

There are three types of leverage:

Labor-saving lever, the power arm is larger than the resistance arm, which is labor-saving but distance-saving;

Laborious lever, the power arm is smaller than the resistance arm, laborious but distance-saving;

Equal arm lever, power arm is equal to resistance arm, neither distance nor effort

Solution: a. The work done to overcome the gravity of the movable pulley is extra work If the gravity of the movable pulley is small, the percentage of useful work in the total work is high, that is, the mechanical efficiency is high; On the contrary, if the gravity of the movable pulley is large, the percentage of useful work in the total work is low, that is, the mechanical efficiency is low, so a is correct;

B. When eating, the force of the index finger and thumb on the chopsticks is the driving force, and the force of the food on the chopsticks is the resistance In this case, the power arm is shorter than the resistance arm, so the chopsticks are a laborious lever, so B is wrong;

c. We use levers sometimes to save effort, sometimes to save distance, so C is wrong;

D. The fixed pulley is essentially an equal arm lever, which is neither labor-saving nor distance-saving, so D is wrong

Therefore, choose a Comment: This question tests students' understanding of simple machinery to know that mechanical efficiency is the ratio of useful work to total work, and that the mechanical efficiency of pulley block is related to material weight and pulley weight; Master the method of judging which lever is a lever: you can judge according to the relationship between the power arm and the resistance arm or according to the actual use of the lever in life.