SURFACE AREAS
AND VOLUMES
6 m
5 km
1.5 m
∴ Length of water
flowing in 30 min.
=
10
2
= 5 km
Speed of
flowing water
=
10 km/hr.
Length of water flowing in 1 hr.
=
10 km
Volume of water flowing in canal in 30 minutes
=
Volume of standing water in field
8 cm
Q. Water in a canal, 6 m wide and 1.5 m deep, is flowing with a
speed of 10 km/h. How much area will it irrigate in 30 minutes,
if 8 cm of standing water is needed?
Q. Water in a canal, 6 m wide and 1.5 m deep, is flowing with a
speed of 10 km/h. How much area will it irrigate in 30 minutes,
if 8 cm of standing water is needed?
Length of the water flowing in 30 minutes (l )
=
=
5 km
Sol.
=
5000 m
=
l
×
b
×
h
=
5000
×
6
×
1.5
10
2
Length of the water flowing in 1 hour
=
10 km
∴
=
5 × 1000 m
Length of the water flowing in 30 minutes (l )
∴
Volume of water flowing
in canal in 30 minutes
=
Volume of standing
water in field
∴
8
100
Area
×
m
8
100
=
l
×
b
×
h
∴
Area
×
h1
l1
×
b1
×
h1
What is the formula to find
Volume of cuboid?
l × b × h
We know that,
Area = l × b
Volume of water flowing in canal in 30 minutes
=
Volume of standing water in field
∴
Q. Water in a canal, 6 m wide and 1.5 m deep, is flowing with a
speed of 10 km/h. How much area will it irrigate in 30 minutes,
if 8 cm of standing water is needed?
=
5000
×
6
×
1.5
8
100
Area
×
∴
Area
=
(5000
×
6
×
1.5)
÷
8
100
=
5000
×
6
×
15
10
100
8
×
4
2
3
2500
5
=
2500 ×
3 ×
75
=
562500 m2
Area
∴
1 hectare = 10,000 m²
∴ Area irrigated will be 562500 m² or 56.25 hectares.
562500
10000
=
=
5625
100
=
56.25 hectares
Sol.