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b) Oscillate about its mean position.

c) Float inside the surface of a liquid.

d) Remain floating on the surface of a liquid.

Conceptual questions (AVG)
1. A steel needle sinks in water but a steel ship floats

2. You have a bag of cotton and an iron bar, each indicating a mass of a 100 kg when
measured on weighing machine. In reality, one is heavier than the other. Can you say
which one is heavier and why?

NUMERICALS (AVG)
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1. Relative density of mercury is 13.6. The density of water is 1000 kg/m . What is the
density of mercury in SI unit?

2. Relative density of silver is 10.8. The density of water is 103 kg/ m3. What is the
density of silver in SI unit?

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3. The volume of 50 g of a substance is 20 cm3. If the density of water is 1 g cm , will
the substance float or sink?

4. The volume of a 500 g sealed packet is 350 cm3. Will the packet float or sink in water
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if the density of water is 1 g cm ? What will be the mass of the water displaced by this
packet?

5. A dining hall has dimensions 50 m × 15 m × 3.5 m. Calculate the mass of air in the
hall. (Given, density of air = 1.30 kg/m )
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6. The mass of an empty 40 litre petrol tank of a vehicle is 8.0 kg. What will be its mass
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when filled completely with a fuel of density 700 kg/m

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