Subject: Science, asked on 24/11/11

Subject: Science, asked on 21/12/11

Subject: Science, asked on 14/10/12

Guys, it's urgent, plz answer them immediately...

Q1. A block weighing 1.0 kg is in the shape of a cube of length 10 cm. It is kept on a horizontal table. Find the pressure on the portion of the table where the block is kept. (ans. 1000Pa)

Q2. Find the thrust acting on the human body due to atmospheric pressure. Take the surface area of a man of middle size to be 1.5m2and atmospheric pressure (1atm) =1.013×105Pa.(ans.15.2 ton wt)

Q3. Calculate the mass of a body whose volume is 2 m3and density 0.52 g/cm3. (ans. 1040 kg)

Q4. A dining hall has dimensions 50m× 15m × 3.5m. Calculate the mass of air in the hall. Given, density of air =1.30kg/m3. (ans. 3412.5 kg)

Q5. A thread of mercury of 10.2 g is in a tube of uniform cross section 0.1cm3. Calculate the length of thread. The density of mercury is 13.6g/cm3. (ans. 7.5cm)

Q6. A cubical block of water is dipped completely in water. Each edge of the block is 1cm in length. Find the buoyant force acting on the block. (ans. 10-2N)

Q7. A body of mass 2.0 kg and density 8000 kg/m3is completely dipped in a liquid of density 800 kg/m3. Find the force of buoyancy on it. (ans. 2N)

Q8. A piece of iron of density 7.8 × 103kg/m3and volume 100 cm3is totally immersed in water. Calculate (a) the weight of the iron piece in air (b) the upthrust and (c) apparent weight in water. (ans. (a) 7.8N (b) 1N (c) 6.8 N)

Q9. A solid body of mass 150g and volume 250cm3is put in water. Will the body float or sink.

Q10. A solid of density 5000kg/m3weights 0.5 kg in air. It is completely immersed in water of density 1000kg/m3.
(a)Calculate the apparent weight of solid in water.(ans. 0.4 kg)
(b)What will be its apparent weight if water is replaced by a liquid of density 8000kg/m3? (ans. 0)

Q11. The mass of a block made of certain material is 13.5 kg and its volume is 15 × 10-3m3. Will the block float or sink in water. Give reason for your answer.

Q12. (a) What is the density of air in NTP? (b)What is the unit of relative density?

Q13. (a) When does a body sinks in a fluid?
(b)Why does a balloon filled with hydrogen gas rise up against gravity?
Q14. (a) Which has greater density: 1 kg of iron or 2 kg of iron?
(b)If a hollow sphere and a solid sphere are both made of the same amount of iron, which sphere has greater average density?

Q15. (a). A body weighs 10 N in air and 8 N when fully immersed in water. How much is the buoyant force acting on the body?
(a) Why are the buoys making the channel in a river are hollow spheres?

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