## pascual 3 years ago if a man is the earth, what is the bacteria? a house or a basketball?

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2. Phascolarctos

are you kidding?

3. kma230

Interesting question! I'll try to work it out here just for fun... $\LARGE{ {V_{Bacteria} \over V_{Man}}={{?}\over{V_{Earth}}}}$ Started out with this simple proportion. For the volume of a bacterial cell, I approximated using a 2 micron long cocci...V = 4/3pi(r^3) = 4/3pi microns^3. For the volume of a man, I found the average density of a human to be 1.01g / cm^3 and the average mass of a man in the US to be 86.6 kg. So, the volume (M/D) comes out to be = 85700 cm^3. Converting microns^3 over to cm^3, the volume of a bacterial cell becomes 4/3pi*10^-12 cm^3. Okay- time to find the ratio! The number comes out to be...4.89*10^-17. Multiply that with the volume of the earth (1.08*10^27 cm^3) gives you 5.29*10^10 cm^3 or 53000m^3. I'm pretty sure that's larger than both the house and the basketball! I likely may have made a mistake somewhere up there^^^^, but it's interesting to get a sense of how large the earth really is. Also, the numbers I used were pretty arbitrary; something to keep in mind.

4. Phascolarctos

ohhh i see. i used to do this kind of problems for physics a long time ago. proportions: we did it between an elephant and an ant. sorry!

5. pascual

wow ! what an answer. i do appreciate it very much. thank you. now i know how to solve things like this. great !

6. kma230

:)