1.C

Một hạt nhân X đang đứng yên thì phát ra một hạt α và biến thành hạt nhân Y. Biết hạt nhân X có số khối là A, hạt α có động lượng là K α . Động năng của hạt nhân Y bằng

A.  K α 2 2 A

B.  K α 2 2 ( A + 4 )

C.  K α 2 2 ( A - 4 )

D.  K α 2 ( A - 4 )

I have many hobbies, but I like reading most. Books are always a good friend to me. It is a good way to improve my vocabularies by exposing many new words. By reading, I get better at concentration because it requires me to focus on what I am reading for long periods. It also opens up the knowledge door for me. Reading books tell me about the world's history, let me see the structure of the brain, or bring me a story of Sherlock Holmes. I think reading is one of the most interesting indoors activity.

Sport helps participants to develop important life skills. It teaches and reinforces discipline and hard work through training and setting and accomplishing goals.

Team sports teach the value of teamwork and trust. Playing sport also thrusts participants into leadership positions, enabling development in this important area.

Through sport, participants experience the highs and lows of excitement and disappointment. Playing sport can help with the ability to overcome disappointment and move on.

Sport helps develop motor skills, co-ordination, vision, problem-solving and strategic thinking – useful skills for academic studies and professional/career development.

Bột sắt nặng và thường có màu đen

Bột lưu huỳnh có màu vàng tươi

Environment is an essential part of our life. A clean environment is necessary for a peaceful and healthy life. An environment is the natural surroundings which helps human beings, animals and other living things to grow and develop naturally. But nowadays, our environment is disturbing in many different ways. Any type of disturbance in the nature’s balance affects the environment totally. It does not only ruin human lives but also affects on all living beings. We can save our environment with the little step taken by everyone on the earth. We should reduce the amount of waste, throwing wastes properly to its place only…and many other simple ways. It is very important to save environment for human existence. When we protect the environment, we are protecting ourselves and our future as well.

In the world's base tank, supercavitation is a method of increasing the maximum. Supercavitation is an effect that is created when a ball of gas forms around an object inside a liquid (try to visualize the vessel's urine surrounded by bubbles). The layer reduces friction 900 times to normal, helping you to be much faster than moving in the water.
To any work that is a great resource for any elaborate military. Extra and fast data, the speed and styles make it easy to locate a sound wave. It's even lacking in the race. Juliet Marine Systems, a worker in Portsmouth, New Hampshire, is trying to make such a shirt. It called to MAIL, created with defensive purpose - to protect naval vessels, and achieve commercial maritime averages. It may also be made in which you make your money in the coast of military games.

Một chiếc xe chạy trên đường thẳng với vận tốc ban đầu là 12 m/s và gia tốc không đổi là 3   m / s 2  trong thời gian 2 s. Quãng đường xe chạy được trong khoảng thời gian này là

A. 30 m.

B. 36 m.

C. 24 m.

D. 18 m.

Read the following passage and choose the letter A, B, C or D to indicate the correct answer to each of the questions from 11 to 20.

Although speech is generally accepted as the most advanced form of communication, there are many ways of communicating without using words. In every known culture, signals, signs, symbols, and gestures are commonly utilized as instruments of communication. There is a great deal of agreement among communication scientists as to what each of these methods is and how each differs from the others. For instance, the basic function of any signal is to impinge upon the environment in such a way that it attracts attention, as, for example, the dots and dashes that can be applied in a telegraph circuit. Coded to refer to speech, the potential for communication through these dots and dashes—short and long intervals as the circuit is broken—is very great. Less adaptable to the codification of words, signs also contain agreed upon meaning; that is, they convey information in and of themselves. Two examples are the hexagonal red sign that conveys the meaning of stop, and the red and white swirled pole outside a shop that communicates the meaning of barber.

Symbols are more difficult to describe than either signals or signs because of their intricate relationship with the receiver’s culture perceptions. In some cultures, applauding in a theater provides performers with an auditory symbol of approval. In other cultures, if done in unison, applauding can be a symbol of the audience’s discontent with the performance. Gestures such as weaving and handshaking also communicate certain culture messages.

Although signals, signs, symbols, and gestures are very useful, they also have a major disadvantage in communication. They usually do not allow ideas to be shared without the sender being directly adjacent to the receiver. Without an exchange of ideas, interaction comes to a halt. As a result, means of communication intended to be used across long distances and extended periods must be based upon speech. To radio, television, and the telephone, one must add fax, paging systems, electronic mail, and the internet, and no one doubts but that there are more means of communication on the horizon.

Applauding was cited as an example of ______.

A. a gesture

B. a signal

C. a symbol

D. a sign