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Comment on Nicolas Tesla Have you made any mistakes in science
As there are still a lot of materials about Nicolas Tesla that have not been declassified in the United States so far, we can not make an accurate evaluation of him. It is estimated that it will be many years before we can know more about this greatest scientist in human history
The principle of DC generator is very similar to that of AC generator. What's the difference in their structure and how do they produce DC?
AC generator can use commutator instead of slip ring, the coil produces alternating current and the direction of the external current supply remains unchanged So produce direct current, no commutator produce alternating current! You can see that the output slide is different
What is the difference between AC motor and DC motor? What are the advantages of DC motor?
Is the connection of DC motor the same as AC? What should DC motor pay attention to? Urgent
The function of motor is to convert electric energy into mechanical energy. Motor is divided into AC motor and DC motor. (1) AC motor and its control. AC motor is divided into asynchronous motor and synchronous motor. Asynchronous motor is divided into single asynchronous motor, two-phase asynchronous motor and
The difference between DC motor and AC motor
DC motors use direct current
AC motors use alternating current
Generally speaking, the motor is AC, the phase change of high voltage DC is too sudden, easy to damage the motor. The battery (electric vehicle) is DC
DC motor refers to the motor using DC power supply (such as dry battery, storage battery, etc.); AC motor refers to the motor using AC power supply (such as home circuit, alternator, etc.)
Application: the structure of DC motor is different from that of AC motor. DC motor has commutator (two opposite half copper rings), while AC motor has no commutator
DC motor is generally used in low voltage circuit, DC power can be easily carried, such as electric bicycle is using DC motor, such as computer fan, recorder motor, etc
Difference method: mainly depends on whether there is a commutator, what kind of power supply is used. DC motor is used for commutator
How to transform temperature into heat energy formula
Q=cm（T1-T2）
C is the specific heat capacity, M is the mass, and () is the temperature difference
What is converted into energy depends on the ratio of energy conversion to heat energy
What is the conversion formula of temperature and energy?
Q = CMT in theory, heat energy is one of the energy. There is no exact formula for the conversion of energy, as long as we follow the first and second laws of thermodynamics, that is, the law of conservation of energy, and the law of entropy
What is the conversion formula between PT100 thermal resistance and temperature?
How much resistance corresponds to how much temperature
When the precise temperature is not known, the temperature of Pt100 increases by 2.5 ℃ for every ohm
Approximate temperature = (resistance - 100) * 2.5100 ohm corresponds to 0 ℃
I want to buy a house around the high-speed railway. Does the high-speed railway have radiation?
I heard that the high-speed railway has strong radiation. I want to know how far away it is from the high-speed railway if I buy a house?
What radiation? Don't listen to the fact that wind is rain. There are too many people in the world who don't understand physics. High speed railway is a train driven by electricity. It's the same principle as ordinary electric locomotive. The only radiation comes from high-voltage line. Moreover, the voltage of high-voltage line of high-speed railway is only 25 kV, much lower than that of high-voltage transmission line. This radiation is not as good as your computer
High speed railway is most afraid of noise. It's better to buy a house 200 meters away from the railway line
After the technical transformation of the railway between cities a and B, the running speed of the train between the two cities is increased from 160km / h to 200km / h, and the running time is shortened by 2.5h. If the distance between cities a and B is XKM, then the equation can be obtained______ ．
Let the distance between city a and city B be XKM. According to the calculation formula of the distance, the time before and after the speed increase can be obtained, and then according to the equivalent relationship, the equation is: x160 − X200 = 2.5
At 8:00 a.m., the center of a typhoon is 200km south of city a and moves towards city a at the speed of 25km / h. at this time, a truck is driving due west from city a at the speed of 100km / h?
I can't understand the previous answers on Baidu, for example:
Set time t
The distance is X:
x^2=(200-25t)^2+(100t)^2
=10625t^2-10000t+40000
When t = 10000 / (10625 * 2) = 8 / 17, X is the smallest
here
200-25t=188.24
100t=47.06
One is 188.24km in the south of the city and the other is 47.06km in the West
Where is "x is the smallest when t = 10000 / (10625 * 2) = 8 / 17",
X & # 178; = 10625t & # 178; - 10000t + 40000 is a quadratic function, because a = 10625 > 0, so x & # 178; has a minimum value, t = - B / 2A
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