Question

Assertion: In taking into account the fact that any object, which floats, must, have an average density less than that of water, during World War I, a number of cargo vessels are made of concrete.
Reason: Concrete cargo vessels were filled with air.
A. Statement I is true, statement II is true and Statement II is a correct explanation for Statement I.
B. Statement I is true, Statement II is true and Statement II is NOT the correct explanation for Statement I.
C. Statement I is true, Statement II is false.
D. Statement I is false, Statement II is true.

Answer 1

Correct Answer - B
The density of concrete, of course, is more than that of water and block of concrete will is like a stone if dropped into water. Concrete cargo were filled with air and as such, average density of cargo vessels is given by
`("Mass of concrete" + "mass of air")/("Volume of concrete" + "volume of air")`
If follows that the average density of cargo vessels must be less than that of water. As a result the concrete cargo vessels do not sink.With the increase in depth the pressure increases according to the formula `Pproph`. Therefore, the force perpendicular to the wall of dam increases. Hence, the dam must have greater strength at base than at top. Due to tis, dams are made thicker at the base than at the top.