#### Term 3- Fluids - Important Questions

9th Standard

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Science

Time : 02:30:00 Hrs
Total Marks : 100
5 x 1 = 5
1. In a fluid, buoyant force exists because pressure at the ____________ of an object is greater than the pressure at the top.

()

bottom

2. The weight of the body immersed in a liquid appears to be_____________ than its actual weight.

()

lesser

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

()

Barometer

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

()

Density

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

()

Atmosphere pressure

6. 5 x 1 = 5
7. Density

8. (1)

Pressure

9. 1 gwt

10. (2)

980 dyne

11. Pascal’s law

12. (3)

hpg

13. Pressure exerted by a fluid

14. (4)

Milk

15. Lactometer

16. (5)

$\frac { Mass }{ volume }$

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

(a) True
(b) False
18. The shape of an object helps to determine whether the object will float.

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

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

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

(a) True
(b) False
22. 10 x 3 = 30
23. On what factors the pressure exerted by the liquid depends on?

24. Why does a helium balloon float in air?

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

26. What is meant by atmospheric pressure?

27. State Pascal’s law.

28. A block of wood of weight 200 g floats on the surface of water. If the volume of block is 300 cm3 calculate the upthrust due to water.

29. Density of mercury is 13600 kg m–3. Calculate the relative density.

30. A body of voloume 100 cc is immersed completely in water contained in a jar. The weight of water and the jar before immersion of the body was 700 g. Calculate the weight of water and jar after immersion.

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

32. Calculate the apparent weight of wood floating on water if it weighs 100g in air.

33. 10 x 5 = 50
34. With an appropriate illustration prove that the force acting on a smaller area exerts a greater pressure.

35. Describe the construction and working of mercury barometer.

36. How does an object’s density determine whether the object will sink or float in water?

37. Explain the construction and working of a hydrometer with diagram.

38. State the laws of flotation.

39. How high does the mercury barometer stand on a day when atmospheric pressure is 98.6 kPa?

40. How does a fish manage to rise up and move down in water?

41. If you put one ice cube in a glass of water and another in a glass of alcohol, what would you observe? Explain your observations.

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

43. Why does a boat with a hole in the bottom would eventually sink?