A metal pipe is 77 cm long. The inner diameter of a cross section is 4 cm, the outer diameter being 4.4cm.
(i) inner curved surface area,
(ii) outer curved surface area
(iii) total surface area
In this question, what do they mean by inner and outer surface area, and cross section?
Answers
Answer:
(i) inner curved surface area
According to the question inner diameter is 4 cm,
then,
Inner radius of a cylindrical pipe =r
1
=
2
innnerdiameter
=(
2
4
)cm=2cm
Height (h) of cylindrical pipe=77 cm,
Curved Surface Area of inner surface of pipe =2πr
1
h
=(2×
7
22
×2×77)cm
2
=968cm
2
(ii) Outer curved surface area
According to the question outer diameter is 4.4 cm
Outer radius of cylindrical pipe =r
2
=
2
outerdiamterer
=(
2
4.4
)cm=2.2cm
Height of cylinder = h = 77 cm,
Curved area of outer surface of pipe = 2πr
2
h
=(2×
7
22
×2.2×77)cm
2
=(2×22×2.2×11)cm
2
=1064.8cm
2
(iii) Total surface area
Total surface area = curved surface area of inner cylinder + curved surface of outer cylinder + 2 × Area of base
Area of base = area of circle with radius 2.2 cm - Area of circle with radius 2 cm
=πr
2
2
−πr
1
2
=
7
22
×((2.2)
2
−(2)
2
)
=
7
22
×(4.84−4)
=
7
22
×(0.84)
=2.74cm
2
Total surface area = curved surface area of inner cylinder + curved surface area of outer cylinder + 2 × Area of base
=968+1064.8+2×2.74
= 2032.8 + 5.76
=2039.08cm
2
Therefore, the total surface area of the cylindrical pipe is
=2039.08cm
2
Answer:
please mark me as brainlist
hope you will understand
Stay home,stay safe
