Chemistry Question!?

Question

If the average radius of the Earth is 3960 miles and it's mass is 6.59 x 10^21 tons, what is it's average density?? Please help. Chem sucks!

Answer 1

The volume of a sphere:

V = 4/3 (pi * r^3)

Density = mass / volume

This will give the answer in tons / mi^3.  Use conversion factors to convert it to gram/cm^3.

Answer 2

idk, sorry i can't be much help, i suck at math.^^' you might be able to google it or something though.  

Answer 3

lol how is this a chem question this is more like physics

D=mass(kg)   /   volume  

Answer 4

this is easy if you know your basic density formula:

density = mass/volume

however, at the moment we only have a radius. BUT, assuming earth is perfectly spherical (not true but for the sake of this question it is fine), we can get the volume using the radius. you probably recall the formula for volume of spheres is

v = (4pi(radius^3))/3

or "four-thirds pi r cubed"

so, in this case

v = (4 x pi x 3960^3)/3

v = 2.6 x 10^11 miles cubed

i can see that you are american, so ill leave it as miles.

im not sure what unit of mass to use, so ill stick with imperial "short" tons:

density = volume/mass

d = 6.59 x 10^21/2.6 x 10^11

d = 2.53 x 10^10 tons/cubic mile.

sorry if the unit is inconvenient but i use the metric system...