Find the approximate volume of metal in a hollow spherical shell whose internal and external radii are 3 cm and 3.0005 cm, respectively.
Given: a hollow spherical shell with internal radii 3cm and external radii 3.0005 cm
To find: the approximate volume of the metal in the hollow spherical shell
Explanation: Let the internal and external radii of the hollow spherical shell be r and R, respectively.
So it is given,
R = 3.0005 and r = 3
And let the volume of the hollow spherical shell be V.
Then we know,
Now substituting the values of R and r, we get
Now using the differentiation to get the approximate value of (3.0005)3.
But the integer nearest to 3.0005 is 3,
So 3.0005 = 3+0.0005
So let a = 3 and h = 0.0005
Hence, (3.0005)3 = (3+0.0005)3
Let the function becomes,
f(x) = x3………(ii)
Now applying first derivative, we get
f’(x) = 2x2……….(iii)
Now let f(a+h) = (3.0005)3
Now we know,
f(a+h) = f(a)+hf’(a)
Now substituting the function from (ii) and (iii), we get
f(a+h) = a3+h(3a2)
Substituting the values of a and h, we get
f(3+0.0005) = 33+(0.0005) (3(32))
⇒ f(3.0005) = 27+(0.0005)(3(9))
⇒ (3.0005)3 = 27+(0.0005)(27)
⇒ (3.0005)3 = 27+0.0135
⇒ (3.0005)3 = 27.0135
Hence the approximate value of (3.0005)3 = 27.0135.
Now substituting this in equation (i), we get
V = 4π(0.0045)
V = 0.018π cm3
Hence the approximate volume of the metal in the hollow spherical shell is 0.018π cm3.