Question

Find the valueme of iron required to make an open box whose external dimensions are 36cm*25cm*16.5cm the box being 1.5cm thick throughout .If 1cm3of iron weighs 8.5grams , find the weight of the empty box in kilograms.
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Answer 1

Answer:

Volume of open box in this case = External box volume - Internal box volume

External volume =

l × b × h

= 14850 cm³

Internal dimensions -

l = 36 - 2 × 1.5 = 33

b = 25 - 2 ×1.5 = 22

h = 16.5 - 1.5 = 15 (Only once 1.5 is subtracted since top of the box is open)

Hence, internal volume =

33 × 22 × 15

= 10890 cm³

Therefore volume of box =

14850 cm³ - 10890 cm³

= 3960 cm³

Now density of box is 8.5 grams per 1 cm³

Weight of empty box

= density × volume

= 8.5 × 3960

= 33660 grams

= 33.66 kg