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CBSE Class 11 Physics Chapter 10 Mechanical Properties of Fluids MCQ
The Class 11 Physics Chapter 10 Mechanical Properties of Fluids explores the fundamental principles governing the behavior of fluids, including liquids and gases. This chapter is essential for understanding how fluids respond to forces and how they interact with their surroundings.
Focusing on multiple-choice questions (MCQs), this section provides students with an opportunity to test their comprehension of key concepts such as pressure, buoyancy, viscosity, and surface tension. Mechanical Properties of Fluids MCQs are designed to reinforce learning by challenging students to apply theoretical knowledge to practical scenarios.
Students can expect questions that cover various topics, including Pascal’s Law, Bernoulli’s Principle, and the effects of fluid dynamics in different contexts. Engaging with these Class 11 Physics MCQs not only aids in solidifying understanding but also prepares students for examinations by enhancing their problem-solving skills and speed. By practicing these questions, students can effectively gauge their grasp of the mechanical properties of fluids, paving the way for success in their academic pursuits.
Class 11 Physics Mechanical Properties of Fluids Overview
Class 11 Physics Chapter 10 Mechanical Properties of Fluids introduces the fascinating world of fluids, which encompass both liquids and gases. It explores how these substances behave under various conditions, focusing on their mechanical properties.
1. Fluid Pressure:
- Understanding Pressure: Imagine standing on a bed of nails. Ouch! Now imagine standing on a single nail. Much worse, right? This illustrates the concept of pressure. Pressure is the force exerted by a fluid per unit area.
- Pascal’s Law: This fundamental principle states that any change in pressure applied to an enclosed fluid is transmitted undiminished to every part of the fluid and the walls of the container. This principle has numerous applications, from hydraulic lifts to braking systems.
- Variation of Pressure with Depth: Have you ever felt the increasing pressure on your ears as you dive deeper into a pool? This is because fluid pressure increases with depth. The deeper you go, the greater the weight of the fluid above you, resulting in higher pressure.
- Atmospheric Pressure: The Earth is surrounded by a blanket of air, which exerts pressure on us and everything around us. This is called atmospheric pressure. We experience it constantly, though we usually don’t notice it. Barometers are instruments used to measure atmospheric pressure.
2. Buoyancy and Archimedes’ Principle:
- Why do some objects float while others sink? This is explained by the concept of buoyancy. Buoyancy is the upward force exerted by a fluid on an object immersed in it.
- Archimedes’ Principle: This crucial principle states that the buoyant force acting on an object immersed in a fluid is equal to the weight of the fluid displaced by the object. This principle helps us understand why ships float, hot air balloons rise, and submarines can submerge and resurface.
3. Surface Tension:
- Why does a water droplet form a spherical shape? This is due to surface tension, which is the force per unit length acting perpendicular to an imaginary line drawn on the liquid surface.
- Origin of Surface Tension: Surface tension arises from the cohesive forces between liquid molecules. These forces tend to minimize the surface area of the liquid, leading to phenomena like the spherical shape of droplets and the rise of liquids in capillary tubes.
4. Viscosity:
- Have you ever tried to stir honey? It’s much thicker and harder to stir than water. This is because of viscosity, which is the resistance offered by a fluid to the motion of an object through it.
- Types of Viscosity:
- Dynamic viscosity: Measures the fluid’s internal resistance to flow.
- Kinematic viscosity: Relates the fluid’s dynamic viscosity to its density.
- Factors Affecting Viscosity: Temperature significantly influences viscosity. Generally, the viscosity of liquids decreases with increasing temperature, while the viscosity of gases increases.
5. Streamline Flow:
- Imagine a river flowing smoothly. This represents streamline flow, where the velocity of fluid particles at any point remains constant with time.
- Equation of Continuity: In streamline flow, the mass flow rate of a fluid remains constant. This principle has important implications in fluid dynamics.
- Bernoulli’s Principle: This principle relates the pressure, velocity, and height of a fluid in streamline flow. It states that as the velocity of a fluid increases, its pressure decreases. This principle has numerous applications, such as in the design of aircraft wings and venturimeters.
Class 11 Physics Mechanical Properties of Fluids MCQ Questions with Answers
1. Pressure in a fluid at rest is the same at all points which are at the same height. This is known as:
(a) Archimedes’ Principle
(b) Bernoulli’s Principle
(c) Stoke’s Law
(d) Pascal’s Law
Answer: (d) Pascal’s Law
Explanation: Pascal’s Law states that when pressure is applied to a confined fluid, it is transmitted equally in all directions throughout the fluid. This means that at the same height within a fluid, the pressure remains constant.
2. Pressure applied to an enclosed fluid is:
(a) increased and applied to every part of the fluid
(b) diminished and transmitted to the wall of the container
(c) increased in proportion to the mass of the fluid and then transmitted
(d) transmitted unchanged to every portion of the fluid and wall of the containing vessel
Answer: (d) transmitted unchanged to every portion of the fluid and wall of the containing vessel
Explanation: According to Pascal’s Law, any pressure applied to a confined fluid is transmitted undiminished throughout the fluid and acts on all parts equally, including the walls of its container.
3. Which liquid is used in an open-tube manometer for measuring small pressure differences?
(a) Oil
(b) Mercury
(c) Water
(d) None of these
Answer: (a) Oil
Explanation: Oil is often used in open-tube manometers because it has a lower density than mercury and can measure small pressure differences effectively without excessive height differences.
4. For which of the following liquids is the liquid meniscus in the capillary tube convex?
(a) Water
(b) Mercury
(c) Both (a) & (b)
(d) None of these
Answer: (b) Mercury
Explanation: Mercury has a convex meniscus in a capillary tube because it does not wet glass, causing it to curve upwards at the edges. In contrast, water has a concave meniscus due to its adhesive properties with glass.
5. A liquid is allowed to flow into a tube of truncated cone shape. Identify the correct statement from the following:
(a) The speed is high at the wider end and high at the narrow end.
(b) The speed is low at the wider end and high at the narrow end.
(c) The speed is same at both ends in a streamline flow.
(d) The liquid flows with uniform velocity in the tube.
Answer: (b) The speed is low at the wider end and high at the narrow end.
Explanation: According to the principle of continuity, when a liquid flows through a tube that narrows, its speed increases as it moves into narrower sections, resulting in lower speed at wider ends.
6. After terminal velocity is reached, the acceleration of a body falling through a fluid is:
(a) equal to g
(b) zero
(c) less than g
(d) greater than g
Answer: (b) zero
Explanation: Terminal velocity occurs when the force of gravity pulling an object downwards equals the drag force from the fluid pushing upwards, resulting in no net force and thus zero acceleration.
7. For flow of a fluid to be turbulent:
(a) Fluid should have high density
(b) Velocity should be large
(c) Reynolds number should be less than 2000
(d) Both (a) and (b)
Answer: (b) Velocity should be large
Explanation: Turbulent flow occurs when fluid moves quickly enough that irregular fluctuations happen, typically indicated by a Reynolds number greater than 2000.
8. In streamline (laminar flow), the velocity of flow at any point in the liquid:
(a) does not vary with time
(b) may vary in direction but not in magnitude
(c) may vary in magnitude but not in direction
(d) may vary both in magnitude and direction
Answer: (a) does not vary with time
Explanation: In laminar flow, particles move smoothly along well-defined paths or streamlines, meaning that their velocity remains constant over time.
9. Smaller the area on which the force acts, greater is the impact. This concept is known as:
(a) impulse
(b) pressure
(c) surface tension
(d) Magnus effect
Answer: (b) pressure
Explanation: Pressure is defined as force per unit area. When you apply force over a smaller area, it results in higher pressure, which can lead to greater impact.
10. The pressure at the bottom of a tank containing a liquid does not depend on:
(a) acceleration due to gravity
(b) height of the liquid column
(c) area of the bottom surface
(d) nature of the liquid
Answer: (c) area of the bottom surface
Explanation: The pressure at a certain depth in a liquid depends on both its height and density but not on how wide or narrow the bottom surface is.
11. Beyond critical speed, the flow of fluids becomes:
(a) streamline
(b) turbulent
(c) steady
(d) very slow
Answer: (b) turbulent
Explanation: When fluid flows beyond its critical speed, it transitions from smooth and orderly (laminar flow) to chaotic and irregular patterns known as turbulent flow.
12. In Bernoulli’s theorem, which of the following is conserved?
(a) Mass
(b) Linear momentum
(c) Energy
(d) Angular momentum
Answer: (c) Energy
Explanation: Bernoulli’s theorem states that for an incompressible fluid flowing without friction, total mechanical energy (kinetic + potential + pressure energy per unit volume) remains constant along a streamline.
13. The excess pressure at depth below the surface of a liquid open to the atmosphere is called:
(a) atmospheric pressure
(b) hydrostatic paradox
(c) gauge pressure
(d) None of these
Answer: (c) gauge pressure
Explanation: Gauge pressure measures how much more pressure exists compared to atmospheric pressure; it accounts for only that excess pressure due to depth.
14. A paint-spray gun is based on:
(a) Bernoulli’s theorem
(b) Archimedes’ principle
(c) Boyle’s law
(d) Pascal’s law
Answer: (a) Bernoulli’s theorem
Explanation: A paint-spray gun uses Bernoulli’s principle by creating low pressure that draws paint from a reservoir and sprays it out as fine droplets.
15. Due to capillary action, a liquid will rise in a tube if angle of contact is:
(a) acute
(b) obtuse
(c) 90°
(d) zero
Answer: (a) acute
Explanation: An acute angle of contact indicates strong adhesive forces between liquid molecules and tube walls, allowing capillary action to pull liquid upward against gravity.
FAQs on Mechanical Properties of Fluids MCQ Class 11 Physics
What are the key concepts covered in the Mechanical Properties of Fluids chapter?
The chapter covers essential concepts such as pressure in fluids, Pascal's Law, buoyancy, viscosity, and surface tension. Understanding these concepts is crucial for solving MCQs related to fluid mechanics.
How can I effectively prepare for MCQs on this topic?
To prepare effectively, students should focus on understanding the fundamental principles and formulas associated with fluid mechanics. Regular practice with sample MCQs, reviewing class notes, and utilizing resources like NCERT textbooks can enhance comprehension and retention.
What types of questions can I expect in the MCQ section?
Questions may include calculations involving pressure differences, buoyant forces, and viscosity, as well as theoretical questions about laws like Pascal’s Law and the behavior of fluids under various conditions. Familiarity with definitions and formulas is also essential.
