Question

A sphere is constructed of two concentric pieces. The inner part is a solid sphere of radius 10.0 cm made of a material with density 4000 kg/m3. The outer part is a spherical shell with
inner radius 10.0 cm and outer radius 20.0 cm. The outer shell has a density 9000 kg/m3.

a) find mass of this sphere
b) what is the average density of this sphere

Answer 1

a)
\[M=\rho_1\frac{ 4 }{ 3}\pi r_1^3 + \rho_2 \frac{4}{3}\pi (r_2^3-r_1^3)\]

Answer 2

b)
\[\rho_{average}=\frac{ allMass }{ all Volume }\]

Answer 3

so a) is 2.1467 x 10 ^11

Answer 4

a) 280,5 kg
b)8374,8 kg/m^3

Answer 5

nvm, i forgot to add the 4/3 in the second part

Answer 6

what do you divde 280648943.7 by to get 280.6?

Answer 7

we work in SI units , so you have to also convert cm to m

Answer 8

yeah i got 2.80 x 10^11

Answer 9

it's impossible check out again

Answer 10

0,1^3= 0,001

Answer 11

got it

Answer 12

so all of mass is 281, how do you find all of volume?

Answer 13

and average density is by definition all the mass divided by all the volume so this volume is simply 4/3 pi *(0,2)^3

Answer 14

its the volume of sphere with outer radius. It's all the volume where all the mass is in

Answer 15

8388

Answer 16

I found 8375 but it's close to it

Answer 17

i keep getting 8385

Answer 18

I substituted 280,5 for mass you 281 so it's correct