SOLUTION: A hollow metal sphere has an internal radius of 20cm and an external radius of 30cm. Given that the density of the metal is 7.8g/cm^3, find the mass of the sphere, expressing ur an

Algebra ->  Volume -> SOLUTION: A hollow metal sphere has an internal radius of 20cm and an external radius of 30cm. Given that the density of the metal is 7.8g/cm^3, find the mass of the sphere, expressing ur an      Log On


   

Question 951049: A hollow metal sphere has an internal radius of 20cm and an external radius of 30cm. Given that the density of the metal is 7.8g/cm^3, find the mass of the sphere, expressing ur answer in kg.
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
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A hollow metal sphere has an internal radius of 20cm and an external radius of 30cm.
Given that the density of the metal is 7.8g/cm^3, find the mass of the sphere, expressing ur answer in kg.
:
Find the vol of the outer and inner spheres V+=+4%2F3pi%2Ar%5E3
4%2F3pi%2A30%5E3 = 113097.3355
4%2F3pi%2A20%5E3 = 33510.3216
--------------------------------------Subtraction gives vol of metal
differ: 79587.014 cu/cm
Find the weight in grams
7.8 * 79587.014 = 620778.71 grams
find the weight in kg
620778.71%2F1000 = 620.78 kg