The outer diameter of a long concrete pipe is 68 cm and its wall thickness is 4 cm. If the water flows at a rate of 9 litres per minute, how long (in m) would the water have flowed in an hour?
Answers
In the figure
MP = AP – AM = (12 – 4) cm = 8 cm
PD = AD – AP = (18 – 12) cm = 6 cm
NQ = AQ – AN = (14 – 8) cm = 6 cm
QD = AD – AQ = (18 – 14) cm = 4 cm
Area of the polygon ABCDEF
= area of ∆AFM + area of trapezium FMPE + area of ∆EPD
+ area of ∆ANB + area of trapezium NBCQ + area of
∆QCD.
= 1
2 × AM × FM +
1
2 (FM + EP) × MP +
1
2 PD × EP +
1
2 ×
AN × NB +
1
2 (NB + CQ) × NQ +
1
2 QD × CQ
= 1
2 × 4 × 5 +
1
2 (5 + 6) × 8 +
1
2 × 6 × 6 +
1
2 × 8 × 5 +
1
2
(5 + 4) × 6 +
1
2 × 4 × 4.
= 10 + 44 + 18 + 20 + 27 + 8 = 127 cm2
Step-by-step explanation:
The outer diameter of a long concrete pipe is 68 cm and its wall thickness is 4 cm. If the water flows at a rate of 9 litres per minute, how long (in m) would the water have flowed in an hour?