How many cubic centimetres of iron are there in an open box whose external dimension are 36 cm, 25 cm and 16.5 cm, the iron being 1.5 cm thick throughout? If 1 cubic cm of iron weighs 15 g, find the weight of the empty box in kg.
Given,
External dimensions of box = 36cm×25cm×16.5cm
Thickness of iron = 1.5 cm
Inner dimensions of box = [(36-3)×(25-3)×(16.5-1.5)]
=33cm×22cm×15cm
Volume of iron used = external volume – internal volume
= 36×25×16.5 – 33×22×15 = 3960 cm3
∵ weight of 1 cm3 iron = 15 gm (given)
∴ weight of 3960 cm3 iron = 3960×15 = 59400 gm = 59.4 kg