Fluids

Samacheer Book Back Questions And Answers For Science Standard 9 “Fluids“

I. Choose the correct answer:
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. An empty plastic bottle closed with an airtight stopper is pushed down into a bucket filled with water. As the bottle is pushed down, there is an increasing force on the bottom. This is because,
(a) more volume of liquid is displaced.
(b) more weight of liquid is displaced.
(c) pressure increases with depth.
(d) All the above.

II. Fill in the blanks:
1. The weight of the body immersed in a liquid appears to be _____ than its actual weight
2. The instrument used to measure atmospheric pressure is _____.
3. The magnitude of buoyant force acting on an object immersed in a liquid depends on _____ of the liquid.
4. A drinking straw works on the existence of _____.

Answers:
1. less
2. Barometer
3. density
4. atmospheric pressure

III. State whether true or false. If false, correct the statement:
1. The weight of fluid displaced determines the buoyant force on an object.
2. The shape of an object helps to determine whether the object will float or not.
3. The foundations of high-rise buildings are kept wide so that they may exert more pressure on the ground.
4. Archimedes’ principle can also be applied to gases.
5. Hydraulic press is used in the extraction of oil from oil seeds.

Answers:
1. True
2. False (The density of an object helps to determine whether the object will floater sink)
3. False (They may exert less pressure on the ground)
4. True
5. True

IV. Match the following:
1. Density                                    A. hρg
2. 1 gwt                                       B. Milk
3. Pascal’s law                             C. Mass / Volume
4. Pressure exerted by a fluid     D. Pressure
5. Lactometer                              E. 980 dyne

Answers:
1. C
2. E
3. D
4. A
5. B

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