80 points Ask two physics questions

1.By: centripetal force formula: f direction = mr 2

mv^2/r

4π^2mr/t^2

Gravitational force f gmm r 2

According to the inscription, gmm, r, 2=mg

So gmm line r line 2=mg line = m*

And because the object loses weight at its equator, it can be seen that the gravitational force it exerts is provided as the centripetal force of the object, so gmm line r line 2=(4 2mr line t 2=m*

Substituting t=24h,g=into the equation in parentheses can solve the r line, and I won't do it for you here!

2.By gmm r 2=mg

Gmm H2=m*25%g

The above two formulas can be solved.

g'=,t'=t=24h,ω=2π/t

mg'=mω^2r

r=g'/ω^2=

2 needs to be solved with integrals, and I don't solve it here.

1 Since t is equal, then r3 m=r3 m (3 refers to the third power), and according to the relation g, (r2*m) (r2*m)= is solved by two sets of equations, and r= is obtained

2 Not within my ability I'm only in high school.

1kj=1000j 1k=℃+

1j= 1℃=

Take it directly to the unit.

1 First of all, I will introduce you to the concept of "zero-point motion".

Zero-point motion: Particles (such as molecules), even when they reach absolute zero, still have half of their energy to make the particles move. is a quantum mechanical concept.

And then back to the "hypothesis of absolute zero", it goes like this:

Absolute zero represents a temperature at which all the molecules and atoms that make up matter cease to move. Motion refers to all spatial, mechanical, molecular, and vibrational motions, including some forms of electronic motion, but it does not include "zero-point motion" in the concept of quantum mechanics. This motion cannot be stopped unless the agglomeration system of the moving particles is dismantled.

Let's look at why this concept of "zero-point motion" quantum mechanics arises:

Absolute zero, the lowest temperature that can theoretically be reached, at which the object has no internal energy. The zero degree that is set as the thermodynamic temperature scale (absolute temperature scale) is called absolute zero. The so-called internal energy obviously refers to the sum of kinetic energy and potential energy.

In other words, under this concept, there is kinetic energy in quantum.

Finally back"Heisenberg's uncertainty principle"Most of the translations have been corrected to the "uncertainty principle":

There is uncertainty in the quantum world, and according to Heisenberg's uncertainty principle, it can be seen that the position and momentum of a particle at a certain moment cannot be accurately given at the same time. An accurate measurement of a particle's position will affect the accuracy of the particle's momentum, and the more accurate the position measurement, the less accurate its momentum will be, and vice versa.

It can be assumed that if you determine his position exactly and then measure his momentum, the result will be inaccurate, and you may understand that there is momentum, and even then it does not contradict the "zero motion" under the "absolute zero hypothesis".

2 The second one is relatively simple, because it is the electrons that flow and the electrons are negative, and we assume that the opposite side of the negative charge is the positive charge, then the opposite of the direction of the negative charge flow is the direction of the positive charge flow.

In fact, in general, all that flows in the current is electrons... Positive charge flow is just a hypothesis, as opposed to the assumption of actual negative charge flow.

Hello, the first question, I don't, I really don't, but the second one says that the direction of the directional movement of the positive charge is the direction of the current, which is actually easy to understand, in fact, the opposite direction of the electron motion is the direction of the current, and the electron shows the negative point.

1. At absolute zero, the substance of the object will become a perfect crystal, and the molecule does not stop running, but runs very regularly.

2. The direction of the current is indeed specified as the direction of the directional operation of the positive charge, but the formation of the current must always have the participation of the positive charge, and the direction of the movement of the positive and negative charges is opposite, so in the conductor without the participation of the positive charge in the movement (such as a solid metal), the direction of the current will naturally become the opposite direction of the operation of the negative charge (electron).

Work is a process quantity, and work is done only when there is a displacement in the direction of the force. However, depending on the research object, it is necessary to consider displacement or relative displacement. Such as friction.

Of course, scum Hui can celebrate Liang stupidity!

According to vt=gt, the honor accompaniment is solved, t=vt g

generation s=1 2*g*t 2

Yield: s=vt2 (2g).