The question of physics is getting faster and faster

No, according to the theorem of conservation of energy, no applied energy is added, and its velocity does not change.

The content of the law Energy is neither created nor disappeared out of thin air, it can only be transformed from one form to another, or from one object to another, and its total amount remains unchanged in the process of transformation or transfer. The law of conservation of energy is widely accepted today, but it has not been rigorously proven.

1) Different forms of energy in nature correspond to different forms of motion: the motion of objects has mechanical energy, the motion of molecules has internal energy, the motion of electric charges has electrical energy, the motion inside the nucleus of an atom has atomic energy, and so on.

2) Different forms of energy can be converted into each other: "Frictional heat generation is the conversion of mechanical energy into internal energy by overcoming friction and doing work; When the water in the kettle boils, the water vapor does work on the lid of the kettle to lift the lid up, indicating that the internal energy is converted into mechanical energy; The electric current does work through the heating wire, which converts electrical energy into internal energy, and so on." These examples illustrate the process by which different forms of energy can be converted into each other and by doing work.

3) If the energy of a certain form decreases, there must be an increase in the energy of other forms, and the amount of decrease and increase must be equal The decrease in the energy of a certain object must have an increase in the energy of other objects, and the amount of decrease and increase must be equal.

A specific expression of conservation of energy.

Conservative mechanical system: In the case of only conservative force doing work, the energy of the system is expressed as mechanical energy (kinetic energy and potential energy), and the conservation of energy is specifically expressed as the law of conservation of mechanical energy.

Thermodynamic system: energy is expressed as internal energy, heat and work, and the expression form of conservation of energy is the first law of thermodynamics.

Relativistic mechanics: In the theory of relativity, mass and energy can be transformed into each other. Taking into account the change in energy caused by the change in mass, the law of conservation of energy still holds. Historically, the law of conservation of energy in this case has also been called the law of conservation of mass and energy.

The total energy flowing into the system must be equal to the total energy flowing out of the system plus the change in the energy inside the system, and the energy can be transformed, from one form to another.

The increase in stored energy in the system is equal to the energy entering the system minus the energy leaving the system.

The significance of the law of conservation of energy.

The law of conservation of energy is one of the most common and important fundamental laws of nature. From physics and chemistry to geology and biology, to cosmic celestial bodies. As small as the inside of the nucleus, as long as there is energy conversion, it must obey the law of conservation of energy.

From daily life to scientific research and engineering technology, this law plays an important role. Human beings' utilization of various energies, such as coal, oil and other fuels, as well as hydropower, wind energy, nuclear energy, etc., is achieved through energy conversion. The law of conservation of energy is a powerful way for people to understand and use nature.

No, you're not giving it energy consistently.

No, in the universe the object is not affected by any force, according to Newton's first law, "all objects without any external force always remain in a state of uniform linear motion or at rest until an external force forces it to change this state", the object will maintain a uniform linear motion.

There is an object in the universe that is now not affected by any external force, such as giving the initial velocity of this stationary object, and when the external force is withdrawn, the object will maintain a uniform linear motion.

There's a problem with your statement.

The centripetal force is not the actual force, and the actual centripetal force of the object cannot be obtained by the formula for calculating the centripetal force, and there will be no situation where the object rotates and changes the centripetal force on itself, so your formula is wrong.

Centripetal force = mg-f support force, at this time, pay attention to the gravity force is greater than the centripetal force, which can provide centripetal force, and the excess will make the object be "pressed" on the ground to form a support force. Since the velocity increases, the required acceleration becomes larger, and n becomes progressively smaller.

But pay attention! The rotation of an object does not determine the magnitude of the centripetal force, which is given by the gravitational force of the object itself minus the supported force.

For the second question, you should be able to figure it out for yourself.

3.The reason why it is said that the gravitational force of an object is approximately equivalent to the gravitational force is understood in this way:

The centripetal force required for the object to rotate with the earth is actually very small, so a large part of the force makes the object "attracted" by the earth, and then produces the supporting force of the ground, which is what we call gravity (which is why the direction of gravity is vertically downward, because the direction we stand in is perpendicular to the tangent of the earth's surface in this place). However, because gravity is much greater than the centripetal force, gravitational force is close to centripetal force.

Bottom line: Because gravity is much greater than the centripetal force, and both forces are given by gravity, gravitational force approximates gravity.

I'm guessing you'll also ask: where did G come from?

g is a constant that has been discovered. Since I am writing this, my thoughts are no longer clear, and I cannot continue to write.

Hope it works.

1. When the earth's rotation gradually increases, does the support force n always equal to the gravitational force?

A:Yes.

The so-called "gravity" is the force observed with the earth as a reference frame that causes an object to accelerate in free fall. Taking the earth as a reference frame, the earth does not have rotation (there is no centripetal force for surface objects), the earth is stationary, and for objects resting on the horizontal ground, it is in a state of equilibrium of two forces--- and the supporting force is always equal to gravity. If you jump out of the Earth and use the space background as a frame of reference, there is no "gravity", only gravitation.

That is, the difference in the selection of reference objects not only affects the description of the motion state of the object, but also affects the force analysis of the object.

PS: It is common sense and a rule to choose which object to choose as a reference object and assume that the object is stationary.

2.According to the formula, if f does not change, ma becomes larger, mg gets smaller, and mass m does not change, does it mean that the gravitational acceleration g becomes smaller? Why?

A:Yes.

Gravity is a component of gravity, and the other is the centripetal force required for an object to rotate with the Earth. As the Earth's rotation accelerates and the centripetal force increases, the gravitational force naturally decreases, which is manifested as a weaker gravitational field, and the g-value, which is the strength of the gravitational field, naturally decreases. In the final analysis, the g-value is just an effect of gravity observed on the ground as a frame of reference, and it is affected by a number of factors:

The speed of the earth's rotation, the latitude, the altitude, etc.

3.If gravity gradually decreases and eventually becomes zero, so that the gravitational force is equal to the centripetal force, then why is it said that gravity is equal to gravitational force for objects near the surface? Obviously the exit gravity is 0, why do you say that gravity is approximately equal to gravitational force?

Answer: "For objects near the surface, the approximate belief that gravity equals gravitational force is only a reference to the slow rotation of the Earth under normal conditions (close to 24 hours of rotation and very small angular velocity). At this time, the centripetal force required by the object near the surface to rotate with the earth is very small, only about 3 (3 thousandths) of the gravitational force, and this centripetal force is completely negligible unless the calculation accuracy is very high.

As a result, the magnitude of gravity is extremely close to the magnitude of gravitational force (very, very, special, especially).

When the Earth's rotation accelerates to the point where the object on the equatorial surface is just "floating", the gravitational force has already decreased to zero (g=0), and the existence of the g-value cannot be measured on the surface of the Earth no matter what is done. The argument that "gravity equals gravitational force for objects near the surface" does not exist. At this time, there is only gravity, no gravity.

You have a good question. This is due to the disconnect between the middle and high schools where we teach physics.

Let me say gravity first: the force experienced by an object due to the attraction of the earth is called gravity. The object of gravity is the Earth.

The direction of gravity is always straight downwards. The gravitational force exerted on an object is proportional to the mass of the object, and the formula is: g=mg, where g is the acceleration due to gravity.

In junior high school g is just a scaling factor. ）

The misconception you have arises lies in this statement. The gravitational force of an object is equal to the supporting force of the object on a horizontal support surface or equal to the tensile force suspended on a thin vertical line. This is the limit of junior high school physics.

This sentence is not to define the magnitude of gravity, but only to explain the measurement method of gravity (we can use spring scales, scales to measure the dependence of gravity).

As you can imagine, the object is also subject to gravity when it is in the air. So, it is conditional that the supporting force is equal to the gravitational force.

Let's talk about your force analysis. I find that your understanding of centripetal force is skewed. It is a force named after the effect.

In a uniform circular motion, the centripetal force should be the resultant force of all external forces. I believe you will experience the centripetal force of an object placed on a horizontal turntable that rotates with the turntable.

There is a problem with your sentence "The gravitational force experienced by an object on the equatorial ground can be decomposed into gravity and centripetal force, and there is f=mg+ma (a is centripetal acceleration)".

The correct statement is "an object on the equatorial ground, subject to the action of gravitational and supporting forces of the ground."

There is mg-n=ma (a is the centripetal acceleration) In reality, the centripetal acceleration is insignificant, so it can be ignored. So mg=n. This is junior high school physics.

Actually、The support force n has always been small gravity。 It's just ignored and not considered. As the Earth's rotation gradually increases, the support force n becomes smaller.

This can be used when you are in the elevator. When the elevator has a downward acceleration, you are weightless. It's just that the acceleration of the elevator is larger, and you can feel it. Whereas, the centripetal acceleration of an object is less when the earth rotates. The principle is the same.

According to your description, I personally think, first of all, the most important thing for this kind of problem is to analyze the force of the object, only the mobile phone analysis picture is right, and then you can show through the equation analysis, the first point, the support force n is not necessarily equal to gravity, because the lower stages of high school are elementary physics, as long as you can do the problem, so the support force n may be equal to the gravity * sin angle angle, etc., the second point, can not be explained, the gravitational acceleration g is about equal to 10, and, I personally suggest, If the landlord prepares for the exam, it is best not to study so carefully, so that it will put the cart before the horse, do more questions, just remember, and if you are interested in the future, you will have the opportunity to study it carefully, I hope the above suggestions can bring you some help, thank you.

As the earth's rotation speed increases, the centripetal force increases, so the gravitational force decreases, but the supporting force is always equal to the gravitational force. Gravity and centripetal force are the two components of gravitational force, the gravitational force does not change, the centripetal force increases, the gravitational force decreases, and the gravitational acceleration decreases (this is only the case at the equator, other changes can be discussed in the parallelogram rule of the synthesized force). The third problem is a problem in reality, which cannot be compared with the situation in the question, and the centripetal force in reality is insignificant, so it can be ignored.

When the earth's rotational speed is zero, gravity is equal to gravitational force equals supporting force, as the rotational speed increases, a part of gravitational force has to provide centripetal force, and gravity gradually decreases, always equal to supporting force. When an object floats up, the gravitational and supporting forces are equal to zero, as if it were completely weightless in space.

The acceleration in MA is the centroid acceleration, and the gravitational acceleration is only defined by people, just like the gravitational acceleration on Earth and the Moon is different. And the gravitational acceleration of the Earth is not the same at different latitudes. When the rotational speed increases, the g will change.

So, imagine that in our lives, do we need three numbers to determine a location? For example, the location of the space station, whether there should be longitude, latitude and altitude, further, we need to determine an event, whether we should also add time, for example, in a news report, a certain event occurred at a certain time and place, this place needs three numbers to represent, and a certain time needs to be represented by a number.

Further, describe the change in the event, for example, event one, I was having breakfast at home today, (note that there are four numbers to represent this event), and event two, today I was having dinner in real kung fu, and here there is a change in the matter. Obviously, there is a time gap, and a space gap between these two things.

Imagine a world without a concept of time, the faster we go, the closer we get to a world without a concept of time, then in order to describe this world without a concept of time, we can think that the time interval between any two events is zero. Now our scientists believe that there is a maximum value of speed, which is the speed of light, and if we live in a world without a concept of time, then there is no time gap between event 1 (breakfast) and event 2 (dinner). But we don't live in that world, so we have breakfast and dinner more than 10 hours apart.

But if our world is getting faster and closer to the world where there is no concept of time, then there may be a difference between breakfast and dinner by 3 hours, or even 1 hour, or even a few minutes. That is to say, 10 hours have passed in our slow world, and only 3 hours, or even 1 hour, or even a few minutes have passed in that fast world, so that time has passed very slowly, and our real time has passed very quickly, so people often say that time flies really fast.