# Virus problem help

1. Sep 3, 2011

### lalahelp

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 0.044 cm3 and 10−9 of that volume consists of viral particles, how many influenza viruses have just landed on you?

2. Relevant equations
V=4/3(pi)(r^3)

3. The attempt at a solution
Volume Influenza A = 4/3(pi)(42.5^3) = 321555 nm
4.4e^11/ 321555= 1368350 viruses landed

What did I do wrong??

2. Sep 3, 2011

### Staff: Mentor

Why 4.4x1011?

3. Sep 3, 2011

### lalahelp

Isnt that the conversion of .044 Cm^3 to nanometers?

4. Sep 4, 2011

### Staff: Mentor

That's what you intended it to be, but seems to me like you made an error in calculations.

I can be wrong, it happened before. But show how you got 1011.

5. Sep 4, 2011

### lalahelp

I got it by multiplying .044*10^-9

6. Sep 4, 2011

### Clever-Name

You're trying to change 0.044 cm^3 to nm^3. It's more complicated than just converting 0.044cm to nm

7. Sep 4, 2011

### lalahelp

Dont I have to multiply the -9 by 3 since its cubed
so It will be .044*10^-27

Correct?

8. Sep 4, 2011

### Staff: Mentor

Better, but still off. That would work for conversion of cubic meter to cubic nanometers, but you are converting cubic centimeters.

Convert cm3 to m3, then m3 to nm3, that's the safest way (and half of that you already did)

9. Sep 4, 2011

### lalahelp

ok thank you!!

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