Do loudspeakers convert electrical energy into kinetic energy?

Do loudspeakers convert electrical energy into kinetic energy?

Right. By pushing the diaphragm to do a certain frequency of reciprocating motion, and then drive the air compression to produce sound. Generally speaking, electric energy is converted into sound energy, and sound energy is strictly a kind of kinetic energy

Given X / y = 3, then the value of X & # 178; + 2xy-3y & # 178; / X & # 178; - XY + Y & # 178; is?
A.12／7 B.7／12 C.-5／7 D.5／7

X / y = 3, so x = 3Y is substituted into X & # 178; + 2xy-3y & # 178; / X & # 178; - XY + Y & # 178; to get 12Y ^ 2 / 7Y ^ 2, so choose a

Two light bulbs marked with 220 V and 40 W are connected in series to the home circuit to calculate the total power

U2/P=R
Calculate the resistance of each 1210 ohm
220 V / (1210 + 1210) Ω = 1 / 11A
Then p = IU is used to calculate the actual total power
If you want to calculate each, divide by 2
The solution is 10W per city
Total 20W

When x is the value, the value of the fraction x-square-x / x-square-1 is 0

(x²-x)/(x²-1)=0
x(x-1)=0
X = 0 or x = 1
x²-1≠0
x≠±1
When x = 0, the value of fraction is 0

(2009 · Liangshan Prefecture) if a conductor is connected to a circuit and the voltage applied to both ends of the conductor is reduced to half of the original value, the resistance of the conductor and the current passing through it will be ()
A. All of them are reduced to half of the original B. all of them remain unchanged C. the resistance remains unchanged and the current is half of the original D. the resistance remains unchanged and the current is twice of the original

Resistance is a property of the conductor itself, which has nothing to do with the current passing through the conductor and the voltage at both ends of the conductor, so the resistance does not change. According to Ohm's law I = ur, when the resistance is constant, the voltage will be reduced by half, and the current will be changed to half of the original. So choose C

How to make the second radical simple

1. Determine the operation order
2. Use the law of operation flexibly
Using multiplication formula correctly
Most denominators should be rationalized in time
In some simple operations, we may be able to reduce the points, so we should not rationalize them blindly

The name plate of an electrical appliance is marked with "220 V 110 W", which is connected to the home circuit
What is the resistance of the appliance?
According to the above question, I = 0.2A
Why not use the formula r = u / I but r = u & # / P

"I = 0.2A" is wrong. I = P / u = 0.5A

Factorization A & # 178; c-abd-abc + A & # 178; D

a²c-abd-abc+a²d
=(a²c+a²d)-ab(d+c)
=a²(c+d)-ab(c+d)
=a(c+d)(a-b)

It is known that the density of copper is 8.9 * 10 ^ 3kg / m ^ 3, and the molar mass of copper is 63.5 * 10 ^ (- 3) kg / mol

The density of copper is 8.9g/cm ^ 3, the molar mass of copper is 63.5g/mol, the volume of copper block is 4.5cm ^ 3, the mass = density × volume, so the mass of copper block is 40.05g, the mass of substance = mass / mol, so the mass of copper block is 40.05g/63.5g/mol ≈ 0.631mol

Define a new operation: observe the following formula:
1⊙3=1×4+3=7 3⊙（-1）=3×4-1=11
5⊙4=5×4+4=24 4⊙（-3）=4×4-3=13
If a ⊙ - 2b = 4, calculate the value of (a-b) ⊙ (2a + b)