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#### Fluids Model Question Paper

9th Standard

Reg.No. :
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Science

Time : 02:00:00 Hrs
Total Marks : 50
6 x 1 = 6
1. The size of an air bubble rising up in water

(a)

decreases

(b)

increases

(c)

remains same

(d)

may increase or decrease

2. Clouds float in atmosphere because of their low

(a)

density

(b)

pressure

(c)

velocity

(d)

mass

3. In a pressure cooker, the food is cooked faster because

(a)

increased pressure lowers the boiling point

(b)

increased pressure raises the boiling point

(c)

decreased pressure raises the boiling point

(d)

increased pressure lowers the melting point

4. In CGS system pressure is measured in ____________.

(a)

dyne cm-2

(b)

dyne

(c)

dyne cm-3

(d)

None

5. Heavy trucks are fitted with six to eight wheels, As area increases, Pressure will ___________.

(a)

decrease

(b)

increase

(c)

remains the same

6. Air gets ____________ as we go down below the sea level like mines

(a)

heavier

(b)

thinner

(c)

greater

(d)

lesser

7. 5 x 1 = 5
8. In a fluid, buoyant force exists because pressure at the ____________ of an object is greater than the pressure at the top.

()

bottom

9. The instrument used to measure atmospheric pressure is _____________.

()

Barometer

10. The magnitude of buoyant force acting on an object immersed in a liquid depends on ___________of the liquid.

()

Density

11. A drinking straw works on the existence of _________.

()

Atmosphere pressure

12. _____________  is an experiment, that demonstrates the principle of buyonacy.

()

Cartesian diver

13. 5 x 1 = 5
14. The weight of fluid displaced determines the buoyant force on an object.

(a) True
(b) False
15. The foundations of high-rise buildings are kept wide so that they may exert more pressure on the ground

(a) True
(b) False
16. Archimedes’ principle can also be applied to gases.

(a) True
(b) False
17. Hydraulic press is used in the extraction of oil from oil seeds.

(a) True
(b) False
18. Pressure exerted by thrust in directly proportional to area of surface on which it acts.

(a) True
(b) False
19. 5 x 1 = 5
20. Density

21. (1)

Milk

22. 1 gwt

23. (2)

980 dyne

24. Lactometer

25. (3)

Pascal's Law

26. Hydraulic Jack

27. (4)

Twice the atmospheric pressure

28. Scuba divers

29. (5)

$\frac { Mass }{ volume }$

2 x 2 = 4
30. Assertion: Pascal’s law is the working principle of a hydraulic lift.
Reason: Pressure is thrust per unit area.
(a) If both assertion and reason are true and reason is the correct explanation of assertion.
(b) If both assertion and reason are true but reason is not the correct explanation of assertion.
(c ) If assertion is true but reason is false.
(d) If assertion is false but reason is true.

31. Assertion: A sleeping mattress is so designed that when you lie on it, a large area of your body comes in its contact.
Reason: This reduces the pressure on the body and sleeping becomes comfortable.
(a) If both assertion and reason are true and reason is the correct explanation of assertion.
(b) If both assertion and reason are true but reason is not the correct explanation of assertion.
(c ) If assertion is true but reason is false.
(d) If assertion is false but reason is true.

32. 5 x 3 = 15
33. Why does a helium balloon float in air?

34. Why it is easy to swim in river water than in sea water?

35. State Pascal’s law.

36. The density of water is 1 g cm–3. What is its density in S.I. units?

37. What is relative density?

38. 2 x 5 = 10
39. Explain the construction and working of a hydrometer with diagram.

40. State the laws of flotation.