How to find Density/ Radius of planetesimals

  • Thread starter Cherrio
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  • #1
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The ice rich planetesimals that formed the cores of the Jovian planets were about 10 times more massive than Earth. Assuming such an ice ball has a density of 2g cm g-3, what would its radius be? How does this compare to Earth's radius.


I need Help =\
 

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  • #2
Kurdt
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What have you tried?
 
  • #3
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I was thinking of multiplying the Earths mass by 10 then using the fomula m=dv

and use the formula for volume of a sphere to get r? IDK
 
  • #4
Kurdt
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Sounds like a good plan.
 
  • #5
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okay so that would be m=dv


10 x 5.97 x 1024 Kg which is 5.97x 1025Kg

then convert from Kg to g 1kg= 1000g

5.97x 1025Kg x 1000 g= 5.97x 1028g
volume of a sphere= (4/3) pi r3

5.97x 1028g= (2g cm-3)((4/3)pir3)

im not to sure how to isolate R
 
  • #6
Kurdt
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You just need a bit of algebraic manipulation. It might help if you use the letters instead of numbers right until the end.
 
  • #7
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ok so it would be


m=d 4/3 pi r3

then m/ d(4/3)pi =r3 ?

then r = cubed root of that anwser?
 
  • #8
Kurdt
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Yes, that looks good.
 

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