Question

(i) Calculate the volume of wood of mass 6000 kg if relative density of wood is 0.8.
(ii) What is a submarine? How can it be made to dive in water and come to surface of water?

Answer 1

(i) Given

Mass of wood , m = 6000 kg

Density of wood , D = 0.8 g / cm³ = 0.8 x 1000 = 800 kg/m³

we know

D = M / V

V = M / D = 6000 / 800

V = 7.5 m³

(ii) Submarine is a water - tight boat which can travel under water like a ship. It is provided with water tanks, when submarine is to dive , water is filled in water tanks density of sea water tanks are emptied and average density of submarine become less than the density of sea water and it rises to surface of water .

While submarine is underwater soldiers can see the enemy activities though periscope.