Give an example of how you can improve the efficiency of your machinery

Reducing the consumption of useless work is the way to improve the efficiency of machinery. For example, friction consumes extra work, and in general machinery, lubricating oil is added to reduce friction and improve mechanical efficiency.

Levers, pulleys, adjust gear ratios.

Mechanical efficiency = useful work divided by total work.

Therefore, reducing wasted work is the best way to improve the efficiency of machinery.

The belt drive is changed to gear transmission, the number of poles of the motor becomes lower, the six poles become four stages, and the four stages become two stages.

The factors that affect mechanical efficiency are: friction, the greater the friction, the greater the pulling force used when lifting the same heavy object, which reduces the mechanical efficiency;

The heavier the object to be lifted, the greater the ratio of useful work to total work, and the higher the mechanical efficiency of the pulley block. Confidant.

The greater the dead weight of the machine itself, the lower the mechanical efficiency

So the answer is: friction, which increases the weight of the object

Answer D Analysis: To answer this question, you need to grasp the permeability and vertical divination: mechanical efficiency is the ratio of useful work to total work, and the method of reducing mechanical efficiency

Answer: Because: mechanical efficiency = useful work (useful work + extra work), so if you want to increase mechanical efficiency, it is to increase the useful work and decrease the extra work, that is, to reduce the ratio of the extra work to the total work cluster, and the time to do the work will not affect the mechanical efficiency, so abc error

Therefore, choose D Comments: This question mainly tests students' understanding and mastery of the methods of increasing fiber and reducing mechanical efficiency

c Take measures to reduce extra work as much as possible.

w useful w total w useful (w useful + w extra) From the above equation, the less extra work, the higher the mechanical efficiency.

I don't know what to ask about.

Answer C Because the total work is the sum of the useful work and the external work of Etansun, and the mechanical efficiency is the ratio of the useful work to the total work, the way to improve the mechanical efficiency should be to reduce the additional work at a regular time by making the nuclear work work a Kai type; or increase the useful work when the total work is fixed; Or increase the useful work when the extra work is certain In this way, the ratio of useful work to the total work increases, and the mechanical efficiency is improved

Analysis: Mechanical efficiency is a physical quantity that indicates the quality of mechanical properties, which is equal to the total mechanical efficiency less than 1 because the total useful work is less than the total work; Power is a physical quantity that indicates how fast or slow an object does work Mechanical efficiency and power are two different physical quantities The use of any machinery cannot save work; Mechanical labor saving has nothing to do with mechanical efficiency a. Mechanical efficiency is the ratio of useful work to total work, and the total work is uncertain, and the mechanical useful work with high mechanical efficiency is not necessarily more This option is wrong; b. Whether the mechanical labor is saved or not has nothing to do with the mechanical efficiency This option is wrong; c. The use of any machinery can not save power This option is wrong; d. Mechanical efficiency is the ratio of useful work to total work, and the larger the proportion of useful work in the total hail work, the higher the mechanical efficiency This option is correct Therefore, d is selected Comments: This question mainly examines our understanding of the physical significance of mechanical efficiency, and at the same time involves the labor-saving situation, power size and principle of imitating sail work

B test question analysis: mechanical efficiency refers to the ratio of useful work to total work, which cannot reflect the specific size of useful work and total work. The total work is equal to the sum of the useful work and the extra work, and the total work must be greater than the useful work, so the mechanical efficiency must be less than 1.

When the total work is constant, increasing the useful work can improve the mechanical efficiency; When the useful work is constant, reducing the total work can improve the mechanical efficiency. The high power in option c only means that the mechanical work is fast, and has nothing to do with the mechanical efficiency; The mechanical efficiency in option d is high, and the ratio of useful work to total work is large, but the size of the total work is not known.

a. The mechanical efficiency of any machinery is always less than 100%, and the mechanical efficiency can be improved by reducing friction and improving the mechanical structure, but not to 100%, which is incorrect;

b. Mechanical efficiency is equal to the ratio of useful work to total work, so to do the same useful work, the smaller the extra work, the higher the mechanical efficiency, this option is correct;

c. Power reflects the speed of the work done by the object, and mechanical efficiency are two completely different concepts, and this option is incorrect;

D, the level of mechanical efficiency has nothing to do with the labor-saving situation of the machinery, the option is incorrect, so choose B

Mechanical efficiency is equal to the ratio of useful work to total work, so a, b are wrong;

In addition to overcoming friction, the extra work of the pulley block is more important to overcome the work done by the gravity of the moving pulley, so the C statement is wrong

To do the same useful work, the less additional work, the greater the proportion of useful work in the total work, and the higher the mechanical efficiency, so the D statement is correct

Therefore, choose D