Complete question is;
The outer radius of a cylindrical metal tube is R and t is the thickness of the metal.
A) Show that the volume, V, of metal in a length, l units, of the tube is given by V = πlt(2R - t)
B) Hence calculate V when R = 7.5. t = 1 and L = 20
Answer:
A)V = πlt(2R - t)
B)V = 879.65
Explanation:
A) Formula for volume of a hollow cylinder is; V = π(R² - r²)h
Where;
R is outer radius
r is inner radius
h is height/length of tube
Now, we are told thickness is t.
Thus; R - r = t
Also, h = l
Thus;
V = π(R² - r²)h
Let's factorize this to get;
V = π((R + r)(R - r))l
V = π((R + r))lt
Since R - r = t
Then, r = R - t
Thus;
V = π(R + R - t)lt
V = πlt(2R - t)
B) when R = 7.5, t = 1 and l= 20;
V = πlt(2R - t)
V = π × 20 × 1(2(7.5) - 1)
V = 879.65