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Homework Help: Virus Area

  1. Aug 31, 2008 #1
    1. The problem statement, all variables and given/known data

    A typical virus is a packet of protein and DNA (or RNA) and can be spherical in shape. The influenza A virus is a spherical virus that has a diameter of 85 nm. If the volume of saliva coughed onto you by your friend with the flu is 0.023 cm3 and 10^-9 of that volume consists of viral particles, how many influenza viruses have just landed on you?

    2. Relevant equations


    3. The attempt at a solution

    4/3*pi*42.5^3=volume of virus

    321555 nm^3 volume of one virus

    (.023cm^3)*(10^-9)= 2.3e-10 cm^3 contains virus = .0023 nl

    Which part of my math is wrong? this just doesnt seem right at all. The volume of one virus is less than what spilled on him.
  2. jcsd
  3. Aug 31, 2008 #2


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    I would convert .023cm^3 into nm^3, then find out how many total virus particles there are, then multiply by 10^-9.
  4. Aug 31, 2008 #3
    how many nanometers are in a centimeter?
  5. Aug 31, 2008 #4
    10 million
  6. Aug 31, 2008 #5
    how many cubic nanometers in a cubic centimeter?
  7. Aug 31, 2008 #6
  8. Aug 31, 2008 #7
    how many nanometers of spit?
  9. Aug 31, 2008 #8


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    .023= 2.3*10^-2. (.023)(10^-9)= 2.3*10^-11.

    You have calculated The volume of one virus and the volume of all the viruses. Convert to the same units and divide the volume of all the viruses by the volume of one to determine how many viruses there were.
  10. Aug 31, 2008 #9
  11. Aug 31, 2008 #10
    how many nanometers of virus?
  12. Aug 31, 2008 #11

    so at this point could I just do 2.3e11/321555?

    and come up with 715274
  13. Aug 31, 2008 #12

    yes, you simply divide
  14. Aug 31, 2008 #13
    thanks alot for the walkthrough help!
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