Q14 of 16 Page 343

State Archimedes’ principle. List its two applications.

Archimedes’ principle states that when an object is fully or partially immersed in a fluid, it experiences an upward force that is equal to the weight of the fluid displaced by it.

The two applications of Archimedes principle are:


i) It is used to design ships and submarines.


ii) It is used to design hydrometer which is used to measure the density of different liquids.


More from this chapter

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12

A hollow plastic ball is taken to the bottom of a through of water and released there (see adjoining figure).


(a) What happens to the ball?


(b) Give a reason for this phenomenon.

 13

A wooden block is kept on a table top. The mass of the wooden block is 5 kg and its dimensions are 40 cm × 20 cm × 10 cm. Find the pressure exerted by the wooden block on the table top if it is made to lie on the table top with its sides of dimensions (a) 20 cm × 10 cm and (b) 40 cm × 20 cm.

 15

Define relative density of a solid. State its unit. How is it related to its density? Write mathematical expression for relative density. What conclusion do you draw if relative density of a substance is (a) greater than 1, (b) less than 1 and (c) equal to 1?

 16

It was raining heavily one day. Prateek made a paper boat and started playing with it in a water pool at road side. He then got his toys and dolls and made them boat riders the boat sank in water. Prateek did not lose courage. He made another boat and used lighter toys as passengers and this time boat did not sink in water.

(a) Why did not sink when loaded with dolls and toys?


(b) Which force is exerted by water on objects immersed in it?


(c) What qualities are shown by Prateek?