Question

7. A cylinder is open at one end. The external
diameter is 10 cm and thickness 2 cm if the height
is 8cm (a) capacity of cylinder (b) volume of
metal used.​

Answer 1

Answer:

b. the volume of the metal used

Answer 2

Let the external diameter be D
and internal diameter be d
R= D/2 = 5cm
Given thickness is 2cm therefore
r=R-2=5-2=3cm
(a) Capacity will be equal to volume of inner cylinder
=pi*r^2 h
=3.14*3*3*8
=226.08cm^3
=226.08 ml
(b) volume of metal used = volume of outer cylinder-volume of inner cylinder
= pi R^2h - pi r^2h
=pi h (R^2-r^2)
=pi h (R+r)(R-r)
=3.14*8(5+3)(5-3)
=3.14*8*8*2
=401.92 cm^3
So the capacity of the cylinder
= 226.08ml
And volume of metal used
=401.92cm^3
Hope it helped