A cubical box is to be constructed with iron sheets 1 mm in thickness. What can be the minimum value of the external edge so that the cube does not sink in water ? Density of iron = 8000 kg/m3 and density of water = 1000 kg/m3.

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1 Answers

Let the required external edge = X cm. 

The surface area of the box = 6X² cm² 

The volume of the iron in the box =6X²*0.1 cm³ =0.60X² cm³ 

The mass of iron in the box = (0.60X²/10⁶ m³)*8000 kg/m³ 

=4.8X²/1000 kg 

The volume of the water displaced =X³ cm³ 

The force of buoyancy 

= (X³/10⁶ m³)*1000 kg/m³ =X³/1000 kg 

In the given condition weight of the box = the force of buoyancy 

→4.8X²/1000 = X³/1000  

→X³ = 4.8 X² 

→X = 4.8 cm.

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