# Unit conversion/density

• nikita33

## Homework Statement

above each square inch of Earth's surface is 14.7 lbs of air. the density of air at sea level is about 1.27g/L. the Earth is 7930 miles in diameter and has a mass of 5.98 x 10^24kg.
a.) use the data above to determine the mass in kg of the Earth's atmosphere.

b.) determine the average density of Earth in grams per milliliter.

## Homework Equations

i think the only relevant equation is d=m/v. everything else seems to be unit conversions. this problem really isn't about the atmosphere, but rather how well i can convert units, and apparently not well.

## The Attempt at a Solution

im looking for the mass of the atmosphere, so i use m = dv
d is 1.27g/mL
i derive v from 4/3pir^3
but i have the radius in miles. does this matter?
i would get (1.27g/mL)(2.55x10^11) since i need it in kg
(1.27 x 10^-3kg)(2.55x10^11) = 3.24 x 10^8 kg/mL?

im sure I am hopelessly wrong. i don't really want to do part b until i get part a.

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