the lateral or curved surface of a closed cylindrical petrol storage tank that is 4.2 in diameter is 4.5 high
Answers
Answer:
Step-byd = 4.2 m so, r = 2.1 m, h = 4.5 m
CSA of cylinder
=
π
d
h
=
22
7
×
4.2
×
4.5
=
59.40
s
q
m
Total surface area of cylinder
=
2
π
r
(
r
+
h
)
=
2
×
(
22
7
)
×
2.1
(
2.1
+
4.5
)
=
2
×
(
22
7
)
×
2.1
×
6.6
=
87.12
s
q
m
-step explanation:
Here, r = 4. 2/ 2 m = 2.1 m, h = 4.5 m
(i) Curved surface area of the storage tank = 2πrh
= 2 × 22 7 × 2.1 × 4.5 m2 = 59.4 m2 Ans.
(ii) Total surface area of the tank = 2πr (h + r)
= 2 × 22/ 7 × 2.1 (4.5 + 2.1) m2
= 44 × 0.3 × 6.6 m2 = 87.12 m2
Let the actual area of steel used be x m2.
Area of steel wasted = 1/ 12 of x m2 = x/ 12 m2. ... (i)
∴ area of the steel used in the tank =( x − x /120 )m2 = 11/ 12 x m2
⇒ 87.12 = 11/ 12 x
⇒ x = 87. 12x 12/ 11 = 95.04 m2
Hence, 95.04 m2 of steel was actually used Ans.