Content Curator
Fluids maintain characteristic physical properties that drive their working while forces are implemented to them. The term ‘fluids’ are normally used to outline both liquids and gases. In different words, it is able to be stated that the materials that have the ability to flow are termed as fluids. Fluids are assumed to be incompressible (i.e., the density of liquid isn't always depending on the variation in stress and stays steady).
Mechanical Properties of Fluids
Ques 1. Pascal’s Law states that ____
- For every action, there is an equal and opposite reaction.
- Force is the time rate of change of momentum.
- For an ideal gas, the pressure is directly proportional to temperature and constant volume and mass.
- A pressure change at any point in the fluid is transmitted throughout the fluid such that the same change occurs everywhere.
Click here for the answer
Answer: d
Explanation: For every action, there is an equal and opposite reaction: Newton’s Third Law
Force is the time rate of change of momentum: Newton’s Second Law
For an ideal gas, the pressure is directly proportional to temperature and constant volume and mass: Ideal Gas Law
A pressure change at any point in the fluid is transmitted throughout the fluid such that the same change occurs everywhere – Pascal’s Law.
Ques 2. Which instrument is used to measure pressure?
- Ammeter
- Speedometer
- Barometer
- Voltmeter
Click here for the answer
Answer: c
Explanation: A “barometer” is a scientific instrument used to measure air pressure. The barometer can also be used to measure the altitude of a region because pressure varies with altitude and especially in forecasting the weather or determining altitude.
Ques 3. A force is applied on a cube of side 3m. Another force, double the magnitude of the previous force is applied on a cube of 1m. Calculate the ratio of pressure on the first cube (P) to the pressure on the second cube (P’)?
- 1/9
- 18
- 1/18
- ½
Click here for the answer
Answer:c
Explanation: P = F/32
P = F/9
P’ = 2F/12
P’ = 2F/1
P/P’ = (F/9)/(2F/1)
= 1/18.
Ques 4. The working of hydraulic machines based on?
- Pascal’s Law
- Newton’s Law of Cooling
- Law of Gravitation
- Ideal Gas Law
Click here for the answer
Answer: a
Explanation: Pascal's Law states that a pressure change at any point in the fluid is transmitted throughout the fluid such that the same change occurs everywhere. This is employed in hydraulic machines by varying cross-sectional areas at required places.
Ques 5. Plants get water through the roots by the action of:
- Capillarity
- Viscosity
- Gravity
- Elasticity
Click here for the answer
Answer: (a) Capillarity
Explanation: Capillary action is the movement of water within the spaces of a porous material due to the forces of adhesion, cohesion and surface tension. It is the ability of a liquid to flow in narrow spaces without the assistance of, and sometimes in opposition to, external forces like gravity.
Ques 6. A force F is applied on a uniform rod of cross-section A and a force F’ is applied on a uniform rod of cross-section 3A. What is the relation between F and F’ if the pressure on both is the same?
- F/F’ = 1/3
- F/F’ = 3
- F’/F = 1/3
- F/F’ = 1/9
Click here for the answer
Answer: a
Explanation: Pressure on first rod (P) = F/A
Pressure on the second rod (P’) = F’/3A
Given;
P = P’
F/A = F’/3A
F/F’ = 1/3.
Ques 7. Pressure decreases if
- only the force is increased but not the area
- only the area is decreases but not the force
- either area decreases or force increases
- the force decreases and/or area increases
Click here for the answer
Answer: d
Explanation: Pressure (P) = Force (F)/Area (A)
From the above equation, we can infer that the pressure is inversely proportional to the area and directly proportional to the applied force.
Hence, the pressure will decrease when force is decreased and/or area is increased.
Ques 8. Choose the wrong statement from the following.
- Small droplets of a liquid are spherical due to surface tension
- Oil rises through the wick due to capillarity
- In drinking cold drinks through a straw, we use the phenomenon of capillarity
- Gum is used to stick two surfaces. In this process, we use the property of Adhesion
Click here for the answer
Answer: (c) In drinking cold drinks through a straw, we use the phenomenon of capillarity.
Explanation: Here, Suction is the air pressure differential between areas. When the pressure in one g part of a system is reduced relative to another, the fluid in the higher pressure region will exert a force relative to the region of lowered pressure.
Ques 9. Study of fluid mechanics called?
- Dynamics
- Fluid Dynamics
- Mechanics
- None
Click here for the answer
Answer: (b) fluid dynamics
Explanation: Fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids—liquids and gases. It has several subtopics, including aerodynamics (the study of air and other gases in motion) and hydrodynamics (the study of liquids in motion).
Ques 10. When the area decreases, pressure___?
- pressure increases
- pressure decreases
- pressure remains constant
- the change in pressure cannot be determined
Click here for the answer
Answer: a
Explanation: Pressure (P) = Force (F)/Area (A)
From the above equation, we can see that the pressure is inversely proportional to area.
Hence, the pressure will increase when the area is decreased.
Ques 11. 3 containers A, B, and C are filled with water as shown in the figure. What is the relation between the pressures at 1, 2, 3? Assume that all jars are stationery.
- 1:1:1
- 1:2:3
- 3:2:1
- 1:2:1
Click here for the answer
Ans. a
Explanation: The pressure at a depth “d” in a liquid is;
P = D*g*d
P = Pressure
D = Density
g = Acceleration due to gravity
d = Depth
Here, d = Total height – h
From the equation, it is evident that the pressure does not depend on the cross-section of the jar when it is stationery. Hence, the pressure at 1, 2, 3 is the same.
Ques 12. Pascal’s Law is valid only for _____
- water
- metals
- fluids
- gases
Click here for the answer
Ans. c
Explanation: Pascal’s law is valid for water, gases, and even other liquids. However, it is not applicable to any other form of matter. Hence, we can conclude that Pascal’s Law is valid only for fluids.
Ques 13. Plants get water through the roots because of
- Viscosity
- Capillarity
- Gravity
- Elasticity
Click here for the answer
Ans. b
Explanation: In plants, one of the tissues used for transport is the “Xylem”. The basic function of the xylem is to transport water from the roots to the stems and the leaves. The transfer of water using xylem in plants occurs using the capillary theory. Hence plants get water through the roots because of capillary action.
Ques 14. The height of a liquid in a fine capillary tube
- Increases as the effective value of acceleration due to gravity are decreased
- Increases with an increase in the density of a liquid
- Decreases with a decrease in the diameter of the tube
- Decreases with an increase in the surface tension
Click here for the answer
Ans. a
Explanation: Since the height of the capillary tube filled is inversely proportional to gravitational pull. Hence, if the gravitational pull decreases then capillary rise decreases.
Ques 15. A capillary tube when immersed vertically in a liquid records a rise of 3 cm. if the tube is immersed in the liquid at an angle of 60° with the vertical, then the length of the liquid column along the tube will be
- 4 cm
- 2 cm
- 8 cm
- 6 cm
Click here for the answer
Ans. d
Explanation: If a tube of a very narrow bore is dipped in a liquid, the liquid in the capillary either ascends or descends wherein a towel soaks water.
Given:
h = 3cm
=
l=?
Ques 16. Water rises up to a height of 5 cm in a capillary tube of radius 2 mm. what is the radius of the radius of the capillary tube if the water rises up to a height of 10 cm in another capillary?
- 2 mm
- 1 mm
- 3 mm
- 5 mm
Click here for the answer
Ans. b
Explanation: Since height of capillary rise is inversely proportional to the radius of the capillary hence,
Ques 17. If the surface of a liquid is plane, then the angle of contact of the liquid with the walls of the container is
- Obtuse Angle
- Acute Angle
- 00
- 900
Click here for the answer
Ans. c
Explanation: The angle of contact with a wall of the container is an angle b/w liquid surface & normal to the wall of the container. Hence for a plane liquid angle of contact is 00.
Ques 18. According to Archimedes's principle, loss of weight of a body immersed in a liquid is equal to
- weight of the liquid displaced
- weight of the total liquid
- weight of the body
- None of the above
Click here for the answer
Ans. a
Explanation: According to Archimede's principle, the loss in weight of the body in the liquid is equal to the weight of the liquid displaced by the immersed part of the body.
Ques 19. Pressure applied to an enclosed fluid is
- Transmitted unchanged to every portion of the fluid and wall of containing vessel.
- Increased in proportion to the mass of the fluid and then transmitted
- Diminished and transmitted to the wall of container
- Increased and applied to every part of the fluid
Click here for the answer
Ans. a
Explanation: Pascal's principle also called Pascal's law states that any pressure applied to a fluid inside a closed system will transmit that pressure equally in all directions throughout the fluid.
Ques 20. A block of ice floats on a liquid of density 1.2 in a beaker then the level of liquid when the ice completely melts
- rises
- remains same
- lowers
- None of these
Click here for the answer
Ans. a
Explanation: The level of the liquid in the beaker will rise. This is because the density of the water formed by the melting of ice is less than that of the density of liquid in the beaker.
Also read:
Comments