Is LGA * LGB equal to LG (AB)

Not necessarily. When a = b = 1, LGA = LGB = lgab = 0

It is known that α = LGA ^ 2 * LGB ^ 2, β = [LG (AB)] ^ 2, γ = [LG (a ^ 2 + B ^ 2)] ^ 2, a > 0, b > 0, a ^ 2 + B ^ 20, b > 0, a ^ 2 + B ^ 2
What can I do besides the special value method?

∵ a > 0. B > 0 and a ^ 2 + B ^ 2 α

If a > 1, b > 1, ab = 100, then the relationship between LGA * LGB and 1 is

lga*lgb=lga*lg(100/a)=lga(2-lga)
=-(lga-1)^2+1
lga>0,
Therefore, the original form

Conservation of energy is one of the basic laws of nature. In the following process of energy conversion, chemical energy is converted into electrical energy
A. Use tide to generate electricity B. use electric lamp to illuminate C. use dry battery to supply power D. use motor to drive water pump to pump water to high place

A. It is the conversion of mechanical energy into electrical energy; B, it is the conversion of electrical energy into light energy; C, it is the conversion of chemical energy into electrical energy; D, it is the conversion of electrical energy into potential energy

How many dimensions of the earth is now? When can we enter into a higher dimension space? What will happen if we enter into a high latitude space? I'd like to delay you for more details
I don't want a simple answer from Jane

Four dimensions, length, width, height, time, other hundreds of dimensions are meaningless

Xiao Meng said he used to weigh 10 pounds. How many kilograms is that?

5359kg

A rectangular sheet of iron is (5a & # 178; + 2b) meters in length and 3a & # 179; meters in width. Cut a small square with a side length of B meters on its four corners, and then fold it into an open box. What is the surface area of the box? 5A & # 178; + 2B, &# 178; is square.. 3A & # 179;, &# 179; is cubic

It's very simple. Notice that the surface area of the uncovered box is five sides. It's a power
We can push it backwards: unfold the uncovered box, and the resulting figure is a rectangle with four squares cut out. Because the figure is unfolded by the box, the area of the figure is the surface area of the box
Then we calculate the area of this figure (i.e. a rectangle with four squares cut off)
Rectangle area: (5 A ^ 2 + 2b) * 3 A ^ 3 = 15 A ^ 5 + 6 A ^ 3 B, then cut off 4 squares: 4 B ^ 2
Get 15 A ^ 5 + 6 A ^ 3 B - 4 B ^ 2
It's up to you^-^

Superconductor and current
According to r = u / I, how can there be current when superconductor resistance is 0?

Suppose there is a current in the superconductor, then the voltage at both ends of the superconductor is 0, which fully conforms to Ohm's law. No matter how large the current is in the superconductor, the voltage difference between the two ends of the superconductor is always 0, so there is no case that you worry about adding a voltage at both ends of the superconductor to cause infinite current
In order to generate current in superconductors, external devices must be used, such as leading current into superconductors through leads, or adding varying magnetic fields to superconducting coils. For mode 1, leads and power supply have internal resistance, so the current cannot be infinite. For mode 2, the rate of change of magnetic field cannot be infinite, so there is no case of infinite current
In the introduction of superconductivity (p129) in the physics textbook for senior high school Volume 2 (compulsory and optional), there is a passage: "the resistance of superconductor is almost zero. If a closed coil is made of superconductor material, once the current is excited in this coil, without power supply, the current can last for dozens of days without decreasing.", These words will make them have a lot of doubts: first, what kind of power supply should be added to the coil? If the circuit needs to be disconnected when the power supply is removed, there can be no current in the circuit, let alone the problem of continuity. Second, no matter how small the voltage (electromotive force) is applied to the electrical appliance with zero resistance, the current generated will be infinite according to Ohm's law I = u / R. but is this possible? Finally, There is no voltage (electromotive force) but current, which is incomprehensible. Isn't it said in the book that the condition of generating current is to maintain voltage at both ends of the conductor?
To answer these questions, we must comprehensively use the knowledge of current, electromagnetic induction and even electromagnetic wave. We may as well explain it after we have learned all the electrical knowledge of high school physics
As we all know, if a metal ring is placed in a variable magnetic field, an induced current will be generated in the ring. For normal metals, when the magnetic field is removed, the current in the ring will quickly decay to zero. For superconducting rings, the situation is completely different. The following figure shows the famous continuous current experiment
When a superconducting ring is placed in a magnetic field and cooled to below the critical temperature, and the magnetic field is suddenly removed, an induced current is generated in the superconducting ring. It is found that the current can persist, and no obvious change of current is found after several years of observation. The explanation for this phenomenon is that the induced electromotive force is generated in the ring due to the change of magnetic flux of the coil, When the current increases, the associated back EMF hinders the further infinite increase of the current. This shows that the current in the superconducting coil can be large but not infinite
Let the self inductance of the coil be l and the original magnetic flux in the loop be Φ. At the beginning, there is no current in the loop
－dΦ/dt = L di/dt
The integral on both sides gives - l i = Φ + C (C is any constant)
When the initial condition is: Φ = Φ, I = 0, C = - Φ
So I = (Φ. - Φ) / L
Once the coil is in a constant magnetic field again and the magnetic flux does not change, the current will be stable at a certain value and will not change
How to understand the above conclusion? From the perspective of energy conversion and conservation, the current in the ring corresponds to a certain amount of energy. Only when this form of energy is converted to other forms of energy, the current will be reduced. Because the resistance is zero and the thermal power of the coil is zero, there is no heat loss and the current will be reduced. Then, is there any other form of energy loss, such as electromagnetic radiation? According to Maxwell's theory, The energy flux density s (pointing vector) of electromagnetic wave is e × h, e and H are electric field strength and magnetic field strength respectively. The constant current excites the constant magnetic field, but the constant magnetic field no longer excites the electric field, that is, e = 0, s = 0, and the coil does not radiate electromagnetic wave. The superconducting coil will maintain a stable current due to the stable energy
Voltage is not a necessary condition for current, it is only necessary to maintain current in resistance. For example, in electromagnetic oscillation, when the oscillation current is maximum, the coil voltage is also zero
It should be pointed out that superconductors have zero resistance only under DC. If the current changes with time, there will be power dissipation
Superconducting coils can maintain a strong current when the voltage is zero or very small, which provides a very attractive prospect for us to store electric energy. It is estimated that if we can make a breakthrough in high temperature superconductivity and use large-scale superconducting materials to store electric energy, China's electric energy will be saved by more than 1 / 3, which does not include the electric energy saved due to the use of superconducting technology in the transmission link

A particle starts to move in a straight line with uniform acceleration from rest, and the acceleration is A1. After time t, it moves in a straight line with uniform deceleration, and the acceleration is A2. If it can return to the starting point after time t, then A1: A2 should be ()
A. 1：1B. 1：2C. 1：3D. 1：4

In the acceleration stage, there are: X1 = 12a1t2 & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; ① the displacement of deceleration stage is: x2 = v0t − 12a2t2 & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; ② where: V0 = a1t & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; X1 = - X

Who can send all the formulas of junior high school physics. It's better to have an explanation
Can I send it directly? I can't see this broken cell phone

1. Velocity: v = s / T 2, gravity: g = mg 3, density: ρ = m / V 4, pressure: P = f / S 5, liquid pressure: P = ρ GH 6, buoyancy: (1) f floating = f '- f (pressure difference) (2) f floating = G-F (apparent gravity) (3) f floating = g (floating, suspension) (4) Archimedes principle: F floating = g row = ρ liquid GV row

Is LGA * LGB equal to LG (AB)