كيلوجرام
الكيلوجرام Kilogram | |
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معلومات عامة | |
نظام الوحدات | النظام الدولي |
وحدة قياس | الكتلة |
الرمز | kg |
التحويلات | |
1 kg في ... | ... يساوي ... |
U.S. customary | ≈ 2.205 الرطل |
وحدات طبيعية | ≈ 4.59×107 Planck masses 1.356392608(60)×1050 hertz [Note 1] |
الكيلوجرام Kilogram، من وحدات القياس الأساسية في النظام الدولي، ويستخدم لقياس الكتلة، ويرمز له بالرمز (kg)، ويقابله الرطل في النظام الإنگليزي، اذ يساوي الرطل الواحد 0,4536 من كج. والكيلوجرام هو عبارة عن ألف (كيلو) من الجرامات.
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التسمية والاستخدام
طبيعة الكتلة
التاريخ
التعريفات المبكرة
النموذج الدولي للكيلوجرام
ثبات النموذج الدولي للكيلوجرام
أهمية الكيلوجرام
تعريفات مستقبلية مقترحة
ثبات الواط
أسلوب عد الذرات
كربون-12
مشروع أڤوگادرو
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تراكم الأيون
قوة الأمبير
تعدد وحدات النظام الدولي للقياس
المفردات
انظر أيضاً
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الهوامش
- ^ One kilogram at rest has an equivalent energy approximately equal to the energy of photons whose frequencies sum to this value.
- ^ Prototype No. 8(41) was accidentally stamped with the number 41, but its accessories carry the proper number 8. Since there is no prototype marked 8, this prototype is referred to as 8(41).
- ^ The sphere shown in the photograph has an out-of-roundness value (peak to valley on the radius) of 50 nm. According to ACPO, they improved on that with an out-of-roundness of 35 nm. On the 93.6 mm diameter sphere, an out-of-roundness of 35 nm (undulations of ±17.5 nm) is a fractional roundness (∆r /r ) = 3.7×10−7. Scaled to the size of earth, this is equivalent to a maximum deviation from sea level of only 2.4 m. The roundness of that ACPO sphere is exceeded only by two of the four fused-quartz gyroscope rotors flown on Gravity Probe B, which were manufactured in the late 1990s and given their final figure at the W.W. Hansen Experimental Physics Lab at Stanford University. Particularly, “Gyro 4” is recorded in the Guinness database of world records (their database, not in their book) as the world’s roundest man-made object. According to a published report (221 kB PDF, here) and the GP‑B public affairs coordinator at Stanford University, of the four gyroscopes onboard the probe, Gyro 4 has a maximum surface undulation from a perfect sphere of 3.4 ±0.4 nm on the 38.1 mm diameter sphere, which is a ∆r /r = 1.8×10−7. Scaled to the size of earth, this is equivalent to an undulation the size of North America rising slowly up out of the sea (in molecular-layer terraces 11.9 cm high), reaching a maximum elevation of 1.14 ±0.13 m in Nebraska, and then gradually sloping back down to sea level on the other side of the continent.
المصادر
- ^ G. Girard (1994). "The Third Periodic Verification of National Prototypes of the Kilogram (1988–1992)". Metrologia. 31 (4): 317–336. Bibcode:1994Metro..31..317G. doi:10.1088/0026-1394/31/4/007.
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وصلات خارجية
BIPM: The IPK in three nested bell jars | |
NIST: K20, the US National Prototype Kilogram resting on an egg crate fluorescent light panel | |
BIPM: Steam cleaning a 1 kg prototype before a mass comparison | |
BIPM: The IPK and its six sister copies in their vault | |
The Age: Silicon sphere for the Avogadro Project | |
NPL: The NPL’s Watt Balance project | |
NIST: This particular Rueprecht Balance, an Austrian-made precision balance, was used by the NIST from 1945 until 1960 | |
BIPM: The FB‑2 flexure-strip balance, the BIPM’s modern precision balance featuring a standard deviation of one ten-billionth of a kilogram (0.1 µg) | |
BIPM: Mettler HK1000 balance, featuring 1 µg resolution and a 4 kg maximum mass. Also used by NIST and Sandia National Laboratories’ Primary Standards Laboratory | |
Micro-g LaCoste: FG‑5 absolute gravimeter, (diagram), used in national laboratories to measure gravity to 2 µGal accuracy |
- National Institute of Standards and Technology (NIST): NIST Improves Accuracy of ‘Watt Balance’ Method for Defining the Kilogram
- The UK’s National Physical Laboratory (NPL): Are any problems caused by having the kilogram defined in terms of a physical artefact? (FAQ - Mass & Density)
- NPL: Avogadro Project
- NPL: NPL watt balance
- Metrology in France: Watt balance
- Australian National Measurement Institute: Redefining the kilogram through the Avogadro constant
- International Bureau of Weights and Measures (BIPM): Home page
- NZZ Folio: What a kilogram really weighs
- NPL: What are the differences between mass, weight, force and load?
- BBC: Getting the measure of a kilogram
- NPR: This Kilogram Has A Weight-Loss Problem, an interview with National Institute of Standards and Technology physicist Richard Steiner
- Avogadro and molar Planck constants for the redefinition of the kilogram
- Realization of the awaited definition of the kilogram
- Media related to Kilogram at Wikimedia Commons