Question

A spherical object has a diameter of 18 cm. It has a spherical inner core with a diameter of 9 cm.

What is the volume of the other layer?
Use 3.14 to approximate pi and express your answer in hundredths.

___cm3

Answer 1

Volume of a sphere = 4/3 pi r^2

First find the volume of the outer sphere.
V = 4/3 * pi * (0.09 ^2) = 0.034 m^3
Next find the volume of the inner speher
V = 4/3 * pi * (0.045^2) = 0.0085
To find the volume of the other layer, subtract the volume of the core from the volume of the Outer surface.
V = 0.034 - 0.0085 = 0.0255 ~ 0.03 m^3

Answer 2

is that what your looking for?

Answer 3

Yea and Ive tried it so many times and lose where I am. im not sure what the answer is :/

Answer 4

V1 - V2 is the volume with a radial amount equal to the differences in the radiuses

\[\frac43\pi R^3-\frac43\pi r^3=\frac43\pi [R^3-r^3]\]

Answer 5

Ive tried that way too but I still dunno what the answer is

Answer 6

what is the difference in the cubic radiuses? lets start there

Answer 7

9?

Answer 8

ok, you might want to reconsider the difference between a diameter and a radius

Answer 9

18-9 = 9 but that is not quite what we are going for

18 and 9 are diameters, we want radiuses, half the diameter

9 and 4.5 are their radiuses

cube them

9^3 and 4.5^3 then subtract them

Answer 10

-637.875

Answer 11

good, but you subtracted in a backwards order :) drop the negative sign and we are good

Answer 12

now multiply that by 4, and divide it by 3

Answer 13

Sorry my internet went out :/ but I got 850.5

Answer 14

Am I right?

Answer 15

Never mind it was 2670.57

Answer 16

637.875(4) = 2551.5

2551.5/3 = 850.5

the last thing to do is multiply it by 3.14

850.5(3.14) = 2670.57