NCERT Solutions For Class 11 Physics Chapter 10 Mechanical Properties of Fluids in Hindi - 2025-26

To solve problems based on Pascal's Law, such as those involving hydraulic lifts, follow this correct method:

• First, identify the two points in the fluid at the same horizontal level where pressure is being applied or measured.
• Apply the principle of Pascal's Law, which states that pressure is transmitted equally, so P₁ = P₂.
• Express the pressure as Force divided by Area for both points: F₁/A₁ = F₂/A₂.
• Carefully substitute the known values of forces and areas, ensuring all units are consistent (e.g., in the SI system).
• Solve the equation algebraically for the unknown variable.

Applying Bernoulli's theorem correctly is crucial for solving problems on fluid dynamics. The key is to select two appropriate points in the streamline flow. The step-by-step method is:

• Identify two points along a streamline in the fluid flow (e.g., at the surface of a tank and at an orifice).
• Write down the Bernoulli's equation: P + ½ρv² + ρgh = constant.
• Apply the equation between the two chosen points: P₁ + ½ρv₁² + ρgh₁ = P₂ + ½ρv₂² + ρgh₂.
• Substitute the known values for pressure (P), density (ρ), velocity (v), and height (h) at both points. Make logical simplifications, such as assuming atmospheric pressure or negligible velocity at a large surface.
• Solve the resulting equation to find the unknown quantity. This method is essential for problems on efflux velocity (Torricelli's law) and Venturi-meters.

A very common mistake when solving problems on viscosity and Stokes' Law is related to units and variables. Students often forget to convert the coefficient of viscosity from CGS units (poise) to SI units (Pa·s or Ns/m²). Another frequent error is using the diameter of a spherical object instead of its radius in the formula for viscous force (F = 6πηrv). To avoid this, always list your variables, check their units, and convert them to the SI system before substituting them into the formula.

In the NCERT solutions, surface tension is primarily used to solve two types of problems:

• Excess Pressure: Calculating the excess pressure inside liquid drops (ΔP = 2S/r) and soap bubbles (ΔP = 4S/r), where 'S' is the surface tension and 'r' is the radius. The solutions show how to correctly apply the formula based on whether it is a drop (one surface) or a bubble (two surfaces).
• Capillary Rise: Determining the height to which a liquid rises in a capillary tube using the formula h = (2S cosθ) / (rρg). The solutions demonstrate the step-by-step application of this formula, paying attention to the angle of contact (θ).

Checking for unit consistency is critical because the formulas in this chapter (like Bernoulli's theorem or Stokes' Law) are derived with the assumption that all quantities are in a coherent system, typically the SI system. A small error, like using pressure in atmospheres, density in g/cm³, or radius in cm while other values are in SI units, will lead to a completely incorrect answer. Establishing a consistent unit system before calculation ensures the physical relationships expressed by the formulas hold true and the final result is dimensionally and numerically correct.

To find the pressure at a certain depth within a fluid, the NCERT solutions follow a clear, step-by-step approach:

• Identify the pressure at the surface of the fluid. If it's open to the air, this is the atmospheric pressure (Pₐ).
• Determine the depth (h) below the surface where you need to calculate the pressure.
• Identify the density (ρ) of the fluid.
• Calculate the gauge pressure (pressure due to the fluid column only) using the formula P_gauge = hρg, where 'g' is the acceleration due to gravity.
• Calculate the absolute pressure by adding the atmospheric pressure to the gauge pressure: P_absolute = Pₐ + hρg.

Yes, absolutely. Vedantu's NCERT Solutions for Class 11 Physics Chapter 10 are exhaustive and cover every single question, including all in-text examples and the questions from the end-of-chapter exercises. This ensures that you have a complete and reliable resource for your exam preparation, structured according to the CBSE 2025-26 guidelines.