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Physics · 术语表

什么是 Scientific notation?

又称: mantissa · exponent

Definition 1.5 High School Physics · 第 1 章 — Orders of Magnitude: Measuring the Universe

A number is in scientific notation when written as

a×10n,1≤a<10,n an integer.a \times 10^{n}, \qquad 1 \leq a < 10, \quad n \text{ an integer.}

The factor aa is the mantissa, the integer nn the exponent. Thus 149 600 000=1.496×108149\,600\,000 = 1.496 \times 10^{8} and 0.000 52=5.2×10−40.000\,52 = 5.2 \times 10^{-4}.

示例

Example 1.7 (Multiplying in scientific notation)

How many Earths fit in the Sun, by mass? With mSun=1.99×1030 kgm_{\text{Sun}} = 1.99 \times 10^{30}\,\mathrm{kg} and mEarth=5.97×1024 kgm_{\text{Earth}} = 5.97 \times 10^{24}\,\mathrm{kg}:

1.99×10305.97×1024=1.995.97×1030−24=0.333×106=3.33×105.\frac{1.99 \times 10^{30}}{5.97 \times 10^{24}} = \frac{1.99}{5.97} \times 10^{30-24} = 0.333 \times 10^{6} = 3.33 \times 10^{5}.

Mantissas and exponents are handled separately; the final answer is re-normalized so that the mantissa lands back in [1,10)[1, 10).

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