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How the size of length? | Education
How the size of length? When we talk about some length must always compare one measure with another
When talking about a length must always compare one measure with another. If you say that you are taller than someone else, you think that the length of the soles of your feet to the top of your head is greater than the length of another person. If you want to Did you know that more than one of your friends, you need to compare your height standing side by side. used instead a measure that will compare your height - sort of a centimeter ruler, or tailor. In this case, instead of directly comparing its height, both of you compare their height with standard length - or the meter rate. | would be impossible to use this method when measuring the standard length in one place was different than the standards in the other. That is why it is important to establish a standard length everywhere the same.
British and American system of length measurement is based on the yards, although there introduce metric measures, it is an ongoing process.
In a legendary story of the Yard was originally defined as the distance from tip of nose English King Alfred to the top of his finger when his hand is stretched out.
first exact standard yard made the 1878th year. consisted of bronze rods exactly yard long, which is guarded by the government. It is called a primary standard and was thought to be a real yard : as it could be measured by the length of the yards and the other bars. These rods are stored in other laboratories throughout the country and are called secondary standards. However, in 1960. it was discovered that the British standard yard tightens the tiny size - about 2 , 5 millionth of a centimeter a year - and it was decided to leave these types of standards of length. in 1963. yard is determined relative to the meter - 1 yard 0.9144 meter.
meter is the standard unit of length in other European countries. Originally, it was determined, the 1791st year, as part desetmilijunski length of the meridian which passes through the Dunkerque in France.
in 1927. meter is again defined as the length of a rod platiniridija kept in Paris. But discovered that the bar changes its length to tiny size, so in 1960. new internationally accepted method for determining measures of length. Founded on the wave length of light emitting atoms. This is the length never changes, the same atom in the same conditions still emits light equal wavelength. was elected one atom of the isotope krypton gas and the meter is now defined as 1 650 763.73 wavelengths emitted by the atom of krypton in some circumstances.
Astronomers sometimes uses the second method of measuring the distance when talking about the distant stars. It is a light year. This is the distance that light travels in one year. As the light travels at a rate of 300 million meters per second, in the year there are about 31.5 million seconds, one light year is 9460 million million meters. This is a huge distance.
Micrometer is an instrument for very precise measurement of small distances. consists of a screw that rotates in the mainstream. As the nut turns to move forward until the tip touches the micrometer object to be measured, the width of items was then given to the ranking.
An ancient unit of length called the cubit and was based on the distance from the angle of the elbow of one man to the top of his middle finger. After surviving measures in pyramids know that the ancient Egyptians took the elbow as the length of about 53 centimeters. One meter has 100 centimeters and every inch of 10 millimeters. Atomic Scientists use the metric units or less. thousandth of a millimeter is called micrometer - or micron - a thousandth of a micrometer to nanometer named. thousandth of a nanometer is called Picómeter, it is a millionth of a millionth of a meter.