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प्रश्न
Why does a ship make of iron not sink in water, while an iron nail sinks in it?
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उत्तर
Density of iron is more than density of water, therefore weight of iron nail is more than wt. of water displaced by it and nail sinks. While shape of iron ship is made in such a way that it displaces more weight of water than its own weight. Secondly, the ship is hollow and the empty space contains air which makes the average density of ship less than that of water and hence ship floats on water.
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संबंधित प्रश्न
A body is held immersed in a liquid. (i) Name the two forces acting on the body and draw a diagram to show these forces. (ii) State how the magnitudes of two forces mentioned in part (i) determine whether the body will float or sink in liquid when it is released. (iii) What is the net force on the body if it (a) sinks and (b) floats?
A block of wood is so loaded that it just floats in water at room temperature. What change will occur in the state of floatation, if
(a) Some salt is added to water, (b) Water is heated?
Give reasons.
A piece of ice floating in a glass of water melts, but the level of water in the glass does not change.
Give reasons.
Hint: Ice contracts on melting.
A weather forecasting plastic balloon of volume 15 m3 contains hydrogen of density 0.09 kg m-3. The volume of equipment carried by the balloon is negligible compared to its own volume. The mass of an empty balloon alone is 7.15 kg. The balloon is floating in air of density of 1.3 kg m-3. Calculate:
(i) The mass of hydrogen in the balloon,
(ii) The mass of hydrogen and balloon,
(iii) The total mass of hydrogen, balloon and equipment if the mass of equipment is x kg,
(iv) The mass of air displaced by balloon and
(v) The mass of equipment using the law of floatation.
A test tube loaded with lead shots weighs 25 gf and floats upto the mark X in water. When the test tube is made to float in brine solution, it needs 5 gf more of lead shots to float upto level X. Find the relative density of brine solution.
A block of wood of volume 25 cm3 floats in water with 20 cm3 of its volume immersed in water.
Calculate:
(1) density of wood
(2) the weight of block of wood.
State the principle of floatation. What can you say about the average density of a ship floating on water?
Explain the following:
A hydrometer is made heavy near the bottom.
How does an object’s density determine whether the object will sink or float in water?
Name different types of Hydrometers with their applications.
