16. Energy

Energy is a fundamental quantity that every physical system possesses; it allows us to predict how much work the system could be made to do, or how much heat it can produce or absorb.

In the past, energy was discussed in terms of easily observable effects it has on the properties of objects or changes in state of various systems. Basically, if something changes, some sort of energy was involved in that change. As it was realized that energy could be stored in objects, the concept of energy came to embrace the idea of the potential for change as well as change itself. Such effects (both potential and realized) come in many different forms; examples are the electrical energy stored in a battery, the chemical energy stored in a piece of food, the thermal energy of a hot water heater, or the kinetic energy of a moving train. To simply say, energy is "change or the potential for change", however, misses many important examples of energy as it exists in the physical world.

Energy can be used not only to produce observable change, it also is used to prevent change in which case unaided observation of this kind of energy can be difficult. For example, looking at a statue holding a 50 pound weight, the presence of energy needed to do so may not be observable. However, if you are holding up the fifty pound weight instead of the statue the need for energy to accomplish this becomes apparent. You can feel the gravitational force on you both when you are moving the weight up and when you are not moving it.

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17. Computer operations

Much of the processing computers can be divided into two general types of operation. Arithmetic operations are computations with numbers such as addition, subtraction, and other mathematic procedures. Early computers performed mostly arithmetic operations, which gave the false impression that only engineers and scientists could benefit from computers. Of equal importance is the computers ability to compare two values to determine if one is larger than, or equal to the other. This is called a logical operation. The comparison may take place between numbers, letters, sounds, or even drawings. The processing of the computer is based on the computer’s ability to perform logical and arithmetic operations.

Instructions must be given to the computer to tell it how to process the data it receives and the format needed for output and storage. The ability to follow the program sets computers apart from most tools. However, new tools ranging from typewriters to microwave ovens have embedded computers, or built-in computers. An embedded computer can accept data to use several options in its program, but the program itself cannot be changed. This makes these devices flexible and convenient but not the embedded computers itself.

With the advent of new computer applications and hardware, the definition of data has expanded to include many types. Numeric data consists of numbers and decimal points, as well as the plus (+) and minus (-) signs. Both arithmetic operations and logical operations are performed on numeric data. This means that numbers can be used for calculations as well as sorted and compared to each other.

Text, or textual data, can contain any combination of letters, numbers and special characters. Sometimes textual data is known as alphanumeric data.

Various forms of data that we can hear and see makes up audio-visual data. The computer can produce sounds, music and even human voice. It can also accept audio information as an input. Data can also take form of drawings and video sequences.

Physical data is captured from the environment. For example, light, temperature and pressure are all types of physical data.

In many large buildings, computer systems process several kinds of physical data to regulate operations. Computers can set off security alarms, control temperature and humidity, or turn lights on and off, all in response to physical data. These applications increase people's safety and save the time and money.

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1) What two major parts could computer operations be divided into?

2) What are arithmetic operations?

3) What are logical operations?

4) Can computer compare two graphical objects?

5) What makes computer so different from other tools?

6) How many are there types of data?