Problem7
Section 1.2: Physical Quantities and Units

Question

Mount Everest, at 29,028 feet, is the tallest mountain on the Earth. What is its height in kilometers? (Assume that 1 kilometer equals 3,281 feet.)

Question by OpenStax is licensed under CC BY 4.0

Final Answer

8.847 km8.847 \textrm{ km}

Solution video

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Video Transcript

This is College Physics Answers with Shaun Dychko To convert the 29028 feet of mount Everest height into kilometers we need to have a conversion factor that has feet on the bottom of it's fraction so that the feet will cancel with the feet in our question. And this by way, is always assumed over one like any number, you can assume it's over one. And so we have feet on the top there and feet on the bottom here which cancel, and leaving us with kilometers in our conversion factor. We put kilometers on top because the question told us to have kilometers in our answer. And so then we fill in the numbers There's 1 kilometer for every 3281 feet. And the arithmetic is 29028 feet divided by 3281 giving us 8.847 kilometers. And we have 4 significant figures in our answer because our conversion factor has only 4 significant figures.

Comments

librarygrl.study·
The conversion factor is assumed to be exact, so would not effect the number of significant figures.
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ShaunDychko·
Hello librarygrl, thank you for your comment. It definitely gave me pause for thought. While some factors are exact, like multiplying by $2$, for instance, and don't limit the number of significant figures in your answer as you correctly say, in this instance the conversion from km to feet is not exact. Looking up [the conversion](https://www.google.com/search?q=1+km+to+feet) with more significant figures $1 \\textrm{ km} = 3280.84 \\textrm{ m}$, so I think in this case it's appropriate to limit the significant figures to 4 in the answer. All the best, Shaun
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