Question

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

• A. $27kg$
• B. $36kg$
• C. $48kg$
• D. $56kg$

Answer 1

The correct option is B $36kg$

The beam has a shape of a cuboid.

Volume of a cuboid of length l, breadth b and height h $=l\times b\times h$

So, the volume of the beam $=9\times 0.4\times 0.2=0.72m^3$
Hence, the weight of the beam if the iron weighs $50kg$ per $m^3=0.72\times 50=36kg$