Solve the equation (square of X-5) - square of X + 3 = 0

Solve the equation (square of X-5) - square of X + 3 = 0

How many watts can 1.5 square copper wire drive

If it is copper wire, the current of 1 square is 4-10a (depending on whether the wire is multiple or single), and the maximum safe current of 1.5 square is 15a, which is about 3KW

The process of electric current doing work is the process that can be transformed into other forms of energy. How much work the electric current does, how much electric energy it consumes, and how much electric energy it can be transformed into other forms of energy
My teacher said that there are three kinds of statements are the same
They are: (1) the process of consuming electric energy; (2) the process of current doing work; (3) the conversion of electric energy into other forms of energy
The teacher explained the three with fans and lights
Please explain these three statements with examples

The electric fan doesn't work when there is no electricity. As you know, when it is powered on, the current is doing work. At this time, your electricity meter will turn, indicating that the electric fan will also turn when it consumes electric energy. This is because the electric energy is converted into the kinetic energy of rotation and the heat energy of heating. I don't know if you can understand it now

When Q walks from B under street lamp a to C, the shadow CD is 1 meter long. When Q walks 2 meters to e, the shadow ef2 meters long. Wang Hua is 1.5 meters tall, and the height of street lamp a is equal to

Easy, you can draw a graph by yourself, let it be at point m when C, and at point n when e, then cm = en = 1.5. From the triangle similar abd and EFN, you can get EF / en = BF / AB --- (/ means division sign), so BF = (AB * EF) / en, similarly BD = (AB * CD) / cm --- (* means multiplication sign), then bf-bd = DF = de + EF = 4

What are the symbols and units of heat?

Q and j joules

A horizontal spring oscillator, if the mass of the oscillator is 0.5kg, the amplitude is 0.1M, the stiffness coefficient of the spring is 2000N / m, what is the maximum acceleration of the oscillator

At the amplitude point, the maximum acceleration is a = 2000 * 0.1 / 0.5 = 400

How to calculate the voltage after the resistance is paralleled on the capacitor of the integral circuit is as detailed as possible,
 

The characteristics of operational amplifier are: the input resistance of positive and negative input poles is extremely large, approximately infinite, and there will be no current flow; the amplification factor is extremely large, approximately infinite. So the characteristics of negative feedback operational amplifier circuit are: 1. The positive and negative input terminals have the same potential, that is, the potential difference between positive and negative input poles is 0; 2

It is known that the mass of the car is m, the horizontal curve is an arc with a radius of 50m, and the maximum friction between the car and the ground is 0.2 times of the weight of the car__________ (g = 10m / S ^ 2)

Let the radius of the curve be r. when turning, the friction force is the centripetal force
0.2mg=mv^2/r
It is not difficult to find the velocity v

The area of isosceles right triangle with 8 cm hypotenuse is equal to______ cm2．

The hypotenuse of an isosceles right triangle is 8cm, the height of the hypotenuse is 12 × 8 = 4cm, and the area of the triangle is 12 × 8 × 4 = 16cm2

As shown in the figure, the mass of the pan and the mass of the spring of a spring platform scale are not taken into account. An object P is placed in the pan at rest. The mass of P is m = 12kg, and the stiffness coefficient of the spring is k = 300N / m. now, a vertical upward force F is applied to p to make p move uniformly and linearly from the rest. It is known that f is a variable force within t = 0.2S, and after 0.2S, f is a constant force, and g = 10m / S2, then the minimum and maximum value of F What are the maximum values?

Let the spring compression light be x at the beginning, then: x = MGK = 120300m = 0.4m, in the first 0.2S time, there is a kinematic formula: x = 12at2, substituting into the data: a = 20m / S2, according to Newton's second law, the force at the beginning is: Fmin = Ma = 12 × 20 = 240n, and the final force after separation is: Fmax mg = ma, that is: Fmax =