Q no. 1, 2, 3, 5:

A 1. A man first swims in seawater and then in river water. 
(i) Compare the weight of seawater and river water displaced by him.
(ii) Where doeshe  find it easier to swim and Why? 

Q 2. State the law of floatation. 

Q. 3. Will a body weight more in air or in vacuum when weighed with a spring balance? Give a reason for your answer.  

Q 5. Shile floating, is the  weight of the body greater than, equat to or lesser than the upthrust? 

 

Dear Student,
Q1-1) We know that the density of seawater is more than the density of river water,So the weight of displaced sea water is more
than the weight of the displaced river water. This weight gives the upward buoyant force to the swimmer. Thus the apparent weight is less in the sea water.
2) Hence he find easier to swim in the sea water.

Q2-The Law of Flotation says that for a floating object, the weight of the object equals the weight of the liquid displaced by the object. We prove this by using Archimedes' Principle with Newton's Second law applied to an object in equilibrium 

Q3- Air is a fluid as and as you know that fluids exert buoyant force on objects. Hence the body will weigh more in air than vaccum

Q5-
The weight is lesser than upthrust . while it sink it moves against the gravity and the upthrust increases.
 

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