Question

Assertion (A) : When a ship enters from river to sea, ship will rise a little.
Reason (R) : The sea water is denser than river water.

• A. (A) is true, but (R) is false.
• B. (A) is false, but (R) is true.
• C. Both (A) and (R) are true, and (R) is the correct explanation of (A).
• D. Both (A) and (R) are true, but (R) is not the correct explanation of (A).

Answer 1

The correct option is C Both (A) and (R) are true, and (R) is the correct explanation of (A).

We know that:
Buoyant force = V⍴g
Due to salt in seawater,
${⍴}_{river}<{⍴}_{sea}$
Salt water has more density. For the same upthrust, a lesser volume of salt water must be displaced.
Therefore ship can support its weight by submerging less volume inside the water in the sea.
Hence, the ship rises, while entering from the river to the sea.