For non physics enthusiasts, please ask you for some doubts in the process of self study of college

Personally, I feel that theoretical mechanics can be simpler, and because you have a deeper understanding of classical physics, it is easier to master theoretical mechanics first.

The latter part of electromagnetism is extremely abstract.

Measure your strength.

I recommend a book, Fundamentals of Physics at Khalid University

This book provides a certain depth of summary and introduction to various physics concepts in college, and it is not too difficult in terms of difficulty.

The foundation of electromagnetism is simpler than theoretical mechanics, but after learning theoretical mechanics, you can have a relatively complete concept of classical physics, and theoretical mechanics has higher requirements for mathematics; Electromagnetism is a relatively broad concept, general electromagnetism belongs to the foundation of electromagnetism, and more in-depth electromagnetism is more difficult.

The field strength generated by the external charge will enter the cavity. It's just that the strength of the "counter-electric field" generated by the charge induced by the cavity just cancels out the field strength generated by the external charge, so it seems that there is no Bi Cong nuclear field strength on the surface!

Therefore, the correct hand-digging answer is B.

Summary. Problems related to college physics.

Send a question.

Hold on. Okay, problem2 trouble to continue to look at it, and I will definitely give you a thumbs up after that.

Wait a minute. Okay, thanks.

Option B analysis: because the weight and height of the two people are the same, so you can ignore the image caused by the difference in the center of gravity and gravity, assuming that the movement of the two people starts to be a uniform acceleration, then, since the rate of A is twice the rate after the same time, then, the acceleration of A (A) = 2a (B), in the process of motion The tensile force of A is larger, because to maintain a large acceleration, f (A) = ma (A), f (B) = ma (B), so f (A) = 2 (B), at this time, Analyzing A, because the tensile force is too large, the net force of the rope (not a person) on the edge of A is equal to f(A)-f(B)=ma(B), the rope moves downward, and the acceleration is a(B), so the actual velocity of A is equal to the motion of A relative to the rope minus the downward velocity of the rope, and the result of the synthesis is that the actual velocity of A is moving upward with the acceleration of a (B)!

At this time, for B, the rope on the side of B itself moves upward with acceleration for a (B) because of A, and B itself moves upward for the rope with the acceleration of a (B) because of the effect of f (B), then the actual motion of B should be the speed of B relative to the rope plus the speed of the rope itself, that is, the upward motion with two accelerations of magnitude a (B)! According to h=1 2t 2, when B moves to the apex, A has just moved half the distance! Note:

My high school physics level, assuming a certain amount of acceleration, if it is a variable acceleration, you need to use the integral, then this a is a certain moment of motion, but every moment A and B have the same correspondence, so the answer is the same after the integration! ）

Hope it helps!

The maximum potential energy is when m and m are at rest.

It is derived from the momentum theorem.

After the bullet is fired into the oscillator at a horizontal velocity, the velocity of the two objects is v1 then (m+m)v1=mv, and it is obtained.

v1=mv/(m+m)

That is, the total kinetic energy at this time is e1=1 2(m+m)v1 2=(mv) 2 2(m+m).

Then the maximum potential energy e=e1==(mv) 2 2(m+m).

The process of m injection into m is very short, and it can be considered that the spring has not had time to deform, and the momentum of (m+m) is conserved.

mvo=(m+m)v

v=[m/(m+m)]vo

Thereafter, the maximum potential energy of the spring = m just after the injection into m (m+m) = (1 2)(m+m)*v 2=[(mvo) 2] [2(m+m)].

VO --- the speed at which the bullet is fired at the oscillator.

Conservation by momentum has mv = m+m) v1

By the conservation of energy there is 1 2 (m+m) v1 2 = emax

i.e. emax = mv) 2 2(m+m).

The maximum potential energy is the kinetic energy of the bullet and the spring oscillator instantaneously after a completely inelastic collision (this is the kinetic energy of enlargement).

m+m)v = m*v

epm = ekm = 1/2 (m+m) *v^2= 1/2 m^2 v^2 / (m+m)

This is just like why other majors have to study advanced mathematics and college English, because there may be people in various disciplines who will use it in scientific research in the future, and they will expand their thinking, which is needed for the development of a big country.

Standard reason: Physics is the source of modern high-tech development, and it is also a scientific method, which can guide people, enhance people's awareness of science and technology, establish a correct understanding of the world, and better transform the world.

College physics is based on the basic knowledge and theory of physics, which is the continuation, extension and deepening of middle school physics, which can cultivate students' scientific literacy, exercise students' thinking ability, and improve students' ability to analyze and solve problems.

The study of university physics plays a very important role in promoting the cultivation of high-quality innovative talents.

It can be seen that it is of great significance to study the teaching of physics in college.

I studied physics in college, but I didn't use it much later because my work wasn't very related to it, and I haven't read much about it over the years. It's that when I was in high school, I bought some physics books that introduced the nature of the universe and other aspects, but I don't know if you can find them now, after all, more than ten years have passed. It was these books that made me choose physics for college, so I just have it at hand, so I would like to recommend it.

1. Stephen. Stephen Hawking's A Brief History of Time and its sequel, The First Promotion Series, Hunan Science and Technology Press; 2. Stephen. Hawking and Roger.

The Nature of Time and Space co-authored by Penrose, the first promotion series, Hunan Science and Technology Press; 3 Peter. Corvinney and Roger. Hayfield, The Arrow of Time, The First Promotion Series, Hunan Science and Technology Press; 4. John.

Barrow's "The Origin of the Universe" - Masterpieces of Science Series 1, published by Shanghai Science and Technology Press; 5. Paul. Davis, The Last Three Minutes of the Universe - Masterpieces of Science Series 2, published by Shanghai Science and Technology Press; 6. Paul. Davis, God and New Physics, First Promotion Series, Hunan Science and Technology Press; 7. Zhao Zheng, "Exploring the Secret of God: From Copernicus to Einstein", Kehai Roaming Series, published by Beijing Normal University Press.

There are so many of these kinds of books. From the "Knowledge of the Universe" to the monthly "Journal of Physics" (which seems to be the name), they are all closely related to physics.

I suggest you go to a bookstore and pick it yourself (go to a larger bookstore, such as Xinhua Bookstore or something).

I'll leave it to you to choose a better physics science book: 1. Look at the publisher. Don't buy some third-rate publishers, the quality is not guaranteed.

2. It depends on whether there is a formula principle or something in it. [Just a suggestion.] Because when you see an interesting principle or something, you can't wait to know "Why?"

If there is no formula or principle, it will be very puzzling. 】

Although I was a sophomore in high school. But I also like physics. I hope it helps you] [mobile phone codeword].

Stephen Hawking's "A Brief History of Time" is an absolute classic.