# Finding the Density of a given object

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1. May 30, 2015

### iJpawn

The density of an object equals its mass divided by its volume. The mass of Earth is 6x10e+24 and its radius is 4000 miles (1.61km = 1mile). What is the density of the Earth in kg/m^3?

V=4/3pi(r)^3. D=M/V

Converting 4000 to Km, I get 6400. After plugging it into the Volume equation, I end up with approximately 1x10e+12. I divide 6x10e+24 by 1x10e+12, and my result is 6x10e^12. Is this the correct way to do the given problem? My answer sheet from my professor does not state this as any of the answers, and I can't think of any other way to approach this equation.

2. May 30, 2015

### iJpawn

The answer should be in kg/m^3.

3. May 30, 2015

### haruspex

Your calculation is hard to follw if you do not state the units at every point. The answer is much too high.
I suspect you erred in converting cu km to cu m.
What units are the given mass in?

4. May 30, 2015

### iJpawn

The mass of earth is given in 6x10e+24kg, sorry for not posting it earlier!

5. May 30, 2015

### haruspex

Ok, but repost your calculation showing units at every step. Omit no steps.