document.write( "Question 40803: A hollow metal sphere has an internal radius of 20 cm and an external radius of 30 cm. Given that the density of the metal is 7.8 g/cm^3 (gramme per cm cube), find the weight of the sphere. (Take PI to be 3.14).\r
\n" ); document.write( "\n" ); document.write( "Please help to solve this question.\r
\n" ); document.write( "\n" ); document.write( "I have tried to calculate the volume of the sphere using the internal radius but then I'm stucked with what I needed to do with the external radius ?\r
\n" ); document.write( "\n" ); document.write( "Thank you very much. \n" ); document.write( "

Algebra.Com's Answer #26202 by stanbon(75887) $\"\"$ $\"About$

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A hollow metal sphere has an internal radius of 20 cm and an external radius of 30 cm. Given that the density of the metal is 7.8 g/cm^3 (gramme per cm cube), find the weight of the sphere. (Take PI to be 3.14).\r
\n" ); document.write( "\n" ); document.write( "V=(4/3)(pi)r^3
\n" ); document.write( "Volume of the shell = Volume of 30cm sphere - Vol of 20cm sphere
\n" ); document.write( "Vol(shell)=(4/3)(pi)[30^3-20^3]
\n" ); document.write( " =(4/3)(3.14)(27000-8000)
\n" ); document.write( " =(4/3)(3.14)(19000)
\n" ); document.write( " =79546 cm^3
\n" ); document.write( "Weight = 7.8(79546)=148200 grams
\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H. \n" ); document.write( "

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