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Ch.7 - Quantum-Mechanical Model of the Atom
Chapter 7, Problem 36

The nearest star to our sun is Proxima Centauri, at a distance of 4.3 light-years from the sun. A light-year is the distance that light travels in one year (365 days). How far away, in km, is Proxima Centauri from the sun?

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1
Understand that a light-year is the distance light travels in one year.
Use the speed of light, which is approximately 299,792 kilometers per second.
Calculate the number of seconds in one year: 365 days/year * 24 hours/day * 60 minutes/hour * 60 seconds/minute.
Multiply the number of seconds in a year by the speed of light to find the distance light travels in one year (1 light-year).
Multiply the distance of 1 light-year by 4.3 to find the distance to Proxima Centauri in kilometers.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Light-Year

A light-year is a unit of distance that represents how far light travels in one year. Since light moves at a speed of approximately 299,792 kilometers per second, a light-year is equivalent to about 9.46 trillion kilometers. This concept is essential for understanding astronomical distances, as it allows us to express vast spaces in manageable terms.
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Distance Calculation

To find the distance to Proxima Centauri in kilometers, one must convert light-years to kilometers. This involves multiplying the number of light-years (4.3) by the number of kilometers in one light-year (approximately 9.46 trillion). Mastery of unit conversion is crucial in chemistry and physics for accurately interpreting and solving problems involving different measurement systems.
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Astronomical Units

Astronomical units (AU) are another way to measure distances in space, where 1 AU is the average distance from the Earth to the Sun, approximately 149.6 million kilometers. While light-years are often used for interstellar distances, understanding AU helps contextualize distances within our solar system. This knowledge is beneficial for comparing distances between celestial bodies.
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