Question

A beam 9 m long, 40 cm wide and 20 cm high is made up of iron which weighs 50 kg per cubic metre. The weight of the beam is

A. 27 kg
B. 48 kg
C. 36 kg
D. 56 kg
​

Answer 1

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Answer: [C] 36 kg.

Given:-

Length = 9 cm.

Breadth = 40 cm.

Height = 20 cm.

Volume of cuboid = length× breadth× height

1m= 100 cm .

⇒40 cm = 0.4 m and 20 cm = 0.2 m

Volume = 9m×0.4m×0.2m

=0.72 m^3

Given that,

1cm^3 weights 50 kg.

⇒0.72 m^3 weights =50× 0.72

= 36 kg

Hope it helps you..♡

Answer 2

Answer:

Option C) 36 kg

$\rule{100}2$

A beam is 9 m long, 40 cm wide and 20 cm high.

Here -

• Length = l = 9 m
• Breadth = b = 40 cm = 40/100 = 0.4 m
• Height = h = 20 cm = 20/100 = 0.2 m

[ To concert m into cm divide with 100 ]

Volume of cuboid = length × breadth × height

Substitute the known values in the above formula. To find the volume of the cuboid.

⇒ 9 × 0.4 × 0.2

⇒ 0.72 m³

The beam is made up of iron of weight 50 kg per m³.

Means,

1 m³ weights = 50 kg/m³

From above calculations we found that volume of cuboid is 0.72 m³. 1 m³ weights 50 kg/m³.

So,

0.72 m³ weights = 50 × 0.72

⇒ 36.0 kg

⇒ 36 kg