What is Coulomb's law

What is Coulomb's law

Coulomb's law in vacuum, two point charges with electric quantity Q1, Q2 and distance R respectively, the electrostatic force of attraction or repulsion is f = kq1q2 / R ^ 2 (Coulomb's law), where k is a constant (k = 8.9880 * 10 ^ 9nm ^ 2C ^ - 2)
Each particle exerts a force of this magnitude on the other particle; this force forms a pair of forces and reactions. If the particles are positively or negatively charged, repulsive force is produced; if the two particles are opposite charged, attractive force is produced
It is also applicable between point charges in air
It is applicable when two charges are stationary or only one charge moves. It is not applicable when two charges move
(3) Coulomb force is a long-range force, so we can't infer from the wrong formula: when R →∞, f →∞. In fact, in this case, two charged bodies can't be regarded as point charges
In addition, for two electrified insulating objects, it can be regarded as the point charge whose charge is concentrated in the collection center, and R is the distance between the collection centers
For two charged metal objects, the redistribution of surface charge should be considered
Coulomb's Law: the force between two static point charges in vacuum is directly proportional to the product of the charged quantity of the two charges. The direction of the force is along the connecting line of the two point charges. The charges with the same sign repel each other and the charges with different signs attract each other. Formula: F = k * (Q1 * Q2) / R ^ 2
Q=C*V
Capacity = capacitance * voltage
The unit is Si standard
When is the formula of Coulomb's law multiplied by K
When calculating, we know Q1, Q2 and R. is it necessary to multiply k = 9 times 10 to get the output
You can tell me when to use Coulomb's law to calculate force without multiplying by K? (of course, the international system of units is used. If the electrostatic system is used, the form of Coulomb's law itself is f = q1q2 / R ^ 2, without coefficient.)
If we know the specific value of q1q2, we need to substitute the value of K.
Physics problems, on the application of Coulomb's law, urgent solution
There are two charged balls a and B on the smooth horizontal plane. The mass of a is twice that of B. release the two balls from rest. The initial acceleration of a is a. after a period of time, the acceleration of B is also a, and the velocity is v. at this time, the acceleration of a is?
Please be more detailed on the third floor. Why is it inverse
Let me be more specific
（1/2)a
A. The Coulomb force of B is always equal,
Because their bodies are subjected to the same force, the greater the mass is, the greater the acceleration is, isn't it? Understand! So their acceleration is inversely proportional to their respective mass, that is, the mass of a is twice that of B, so the acceleration of a is always 1 / 2 of B. therefore, when the acceleration of B is a, the acceleration of a is a / 2
If you ask me to do this, many conditions are unnecessary. Look, is there any loophole in what I said
Suppose the mass is 2M and B is m
According to Newton's second law, the force on the other side is ma
According to Newton's third law, the forces act on each other, so the force on a is ma
It can be concluded that the acceleration of a at that time is 2 / A
Don't look at the process of Coulomb's law, because it's a variable acceleration motion. It's best to calculate it according to a simple method. Don't use the content of the chapter "uniform variable speed motion"
If you ask me to do this, many conditions are unnecessary. Look, is there any loophole in what I said
Suppose the mass is 2M and B is m
According to Newton's second law, the force on the other side is ma
According to Newton's third law, the forces act on each other, so the force on a is ma
It can be concluded that the acceleration of a at that time is 2 / A
Don't look at the process of Coulomb's law, because it's a variable acceleration motion. It's best to calculate it according to a simple method. Don't use the uniform variable speed motion. Put it away
The forces on a and B balls are always equal
At the beginning a acceleration = a
A is twice the mass of B
So the acceleration of B is a / 2
Then the acceleration of B becomes a
And the quality remains the same
According to Newton's second law, f = m * a
The Coulomb force between the two becomes twice the original
The mass of ball a is constant, so the acceleration of ball a is 2A
Let the mass of a be Ma and the mass of B be MB, then according to the meaning of the title, Ma = 2MB, the initial force is F1 = ma * a = 2MB * a, and the Coulomb force received by the two balls is the force and reaction force. According to Newton's third law, the Coulomb forces on the two balls are equal in magnitude and opposite in direction. Later, the acceleration of ball B is a, then according to Newton's second law, F2 = MB * a, and the force on ball a is also F2, Then F2 = ma * A1 = 2MB * A1 = MB * a, A1 = (1 / 2) a... expansion
Let the mass of a be Ma and the mass of B be MB, then according to the meaning of the title, Ma = 2MB, the initial force is F1 = ma * a = 2MB * a, and the Coulomb force received by the two balls is the force and reaction force. According to Newton's third law, the Coulomb forces on the two balls are equal in magnitude and opposite in direction. Later, the acceleration of ball B is a, then according to Newton's second law, F2 = MB * a, and the force on ball a is also F2, Then there are F2 = ma * A1 = 2MB * A1 = MB * a, A1 = (1 / 2) a, and A1 = (1 / 2) a
On all formulas of simple harmonic motion
It's about speed
This is a physics problem. There is no formula. The speed is the highest at the balance position and the lowest at the farthest from the balance position. You won't be asked to calculate this in the exam
......
Is there a formula? It needs to be analyzed in detail
The formula of simple harmonic motion
X = ACOS (WT + a), can't type Greek letter, sorry
A is the amplitude of simple harmonic motion, W is the circular frequency, and a is the initial phase
What is the physical meaning of the physical quantity "phase" describing simple harmonic motion?
How to define "Xiang"? What to describe? How to understand the concept of "Xiang"?
What is Pi?
It is used to describe the initial state. For example, the spring oscillator starts timing from the equilibrium position. When t = 0, it is in the equilibrium position, and the velocity direction is the same as the specified direction. In the expression, phase = 0 (opposite velocity direction, phase = Pi); when t = 0, the distance from the equilibrium position = (1 / 2) a, the velocity direction is positive, then phase = (2 / 3) PI
It's a physical quantity that describes the state
The phase describing the initial state is the primary phase
On the second floor. Generally speaking, for a wave with F (x, t) = a * cos (WT KX + phi), - KX + phi is the phase of x position
PI is 3.1415
All the formulas of the law of universal gravitation
F = ma or a = f / MA {determined by the external force and consistent with the direction of the external force
F = GMM / R2, gravitation only applies to the interaction between two particles, especially the motion between celestial bodies! In the motion of celestial bodies, gravitation provides centripetal force, that is, GMM / r2 = MV2 / R. here, R2 refers to the square of the distance between two stars, V2 also refers to the square of the speed of the star moving centripetally around the central celestial body! When the distance between two objects is large, it can not be ignored, Gravitation is not applicable to calculate the gravitation between them! If you can, it is only an approximation!
High school experience
Don't set the formula
Understanding is everything
F=GMm/r2
F=GMm/r^2
R ^ 2 is the square of the distance between two stars
Mm is the mass of each component
G is the constant of gravitation
G = 6.67259 × 10 ^ - 11 m ^ 3 / (kg · s ^ 2)
If you have time, it's more helpful to deduce by yourself
There is nothing to say, just want to say that the law of gravitation can not be deduced, it is an empirical formula based on experiments
What are the formulas of the law of universal gravitation
You're talking about planets orbiting stars, right?
At this time, all gravity provides centripetal force
GMm/R²=mv²/R=mω²R=m4π²/T²·R
Note that R is the radius of the orbit!
In addition, if the gravity of objects on the surface of a general point star is approximately equal to that of universal gravitation
GMM / R & sup2; = mg, GM = GR & sup2;
Note: here r refers to the radius of the planet itself, G refers to the acceleration of gravity on the surface of the planet!
It's not easy to code so many words,
What is the formula of the law of gravitation? Explain what each letter stands for
Gravity is the most common force in nature. It is also called gravity sometimes. In particle physics, it is called gravitational interaction. Strong, weak and electromagnetic forces are called four basic interactions
The formula of Newton's law of universal gravitation
There are many expressions of formulas
But only one can be used in high school
F=G*M*m/R^2
Where R is the distance, G represents the gravitational constant of 6.67259 × 10 ^ - 11 (n · m ^ 2) / (kg ^ 2),
M m is the mass of two objects
This expression can only be used between particles, stars and two spheres with uniform density
The teacher should have talked about a classic model
Nested particles in rings and enveloped particles in large balls
You can't do that. If it's not applicable, you can use geometric elimination
Using symmetry
That's all you can talk about and test in high school