Fluid Mechanics · Physics · AP EAPCET
MCQ (Single Correct Answer)
A wire of length 20 cm is placed horizontally on the surface of water and is gently pulled up with a force of $1.456 \times 10^{-2} \mathrm{~N}$ to keep the wire in equilibrium. The surface tension of water is
If two soap bubbles each of radius 2 cm combine in vacuum under isothermal conditions, then the radius of the new bubble formed is
When the temperature increases, the viscosity of
In a water tank, an air bubble rises from the bottom to the top surface of the water. If the depth of the water in the tank is 7.28 m and atmospheric pressure is 10 m of water, then the ratio of the radii of the bubble at the bottom of the tank and at the top surface of the water is
(Temperature of the water in the tank is constant)
Water flowing through a pipe of area of cross-section $2 \times 10^{-3} \mathrm{~m}^2$ hits a vertical wall horizontally with a velocity of $12 \mathrm{~ms}^{-1}$. If the water does not rebound after hitting the wall, then the force acting on the wall due to water is
If two soap bubbles $A$ and $B$ of radii $r_1$ and $r_2$ respectively are kept in vacuum at constant temperature, then the ratio of masses of air inside the bubbles $A$ and $B$ is
An aeroplane of mass $4.5 \times 10^4 \mathrm{~kg}$ and total wing area of $600 \mathrm{~m}^2$ is travelling at a constant height. The pressure difference between the upper and lower surfaces of its wings is (Acceleration due to gravity $=10 \mathrm{~ms}^{-2}$ )
In a hydraulic lift, if the radius of the smaller piston is 5 cm and the radius of the larger piston is 50 cm , then the weight that the larger piston can support when a force of 250 N is applied to the smaller piston is
A liquid drop of diameter $D$ splits into 3375 small identical drops. If $S$ is the surface tension of the liquid, then the change in the surface energy in the process is
If water flows with a velocity of $20 \mathrm{cms}^{-1}$ in a pipe of radius 2 cm , then the flow is (The coefficient of viscosity of water is $10^{-3} \mathrm{~kg} \mathrm{~m}^{-1} \mathrm{~s}^{-1}$ and density of water is $10^3 \mathrm{~kg} \mathrm{~m}^{-3}$ )
Water is flowing in streamline manner in a horizontal pipe. If the pressure at a point where cross-sectional area is $10 \mathrm{~cm}^2$ and velocity $1 \mathrm{~ms}^{-1}$ is 2000 Pa , then the pressure of water at another point where the cross-sectional area $5 \mathrm{~cm}^2$ is
A hydraulic lift is shown in the figure. The movable pistons $$A, B$$ and $$C$$ are of radius $$10 \mathrm{~cm}, 100 \mathrm{~m}$$ and 5 cm respectively. If a body of mass 2 kg is placed on piston $$A$$, the maximum masses that can be lifted by piston $$B$$ and $$C$$ are respectively.
In a hydraulic lift, compressed air exerts a force $$F$$ on a small piston of radius 3 cm . Due to this pressure the second piston of radius 5 cm lifts a load of 1875 kg . The value of $$F$$ is (Acceleration due to gravity $$=10 \mathrm{~ms}^{-2}$$)
In a $$U$$-shaped tube the radius of one limb is 2 mm and that of other limb is 4 mm . A liquid of surface tension $$0.03 \mathrm{~Nm}^{-1}$$, density $$1500 \mathrm{~kg} \mathrm{~m}^{-3}$$ and angle of contact zero is taken in the tube. The difference in the heights of the levels of the liquid in the two limbs is (Acceleration due to gravity $$=10 \mathrm{~ms}^{-2}$$)
A steady flow of a liquid of density $$\rho$$ is shown in figure. At point 1, the area of cross-section is $$2 A$$ and the speed of flow of liquid is $$\sqrt{2} \mathrm{~ms}^{-1}$$. At point 2 , the area of cross-section is $$A$$. Between the points 1 and 2, the pressure difference is $$100 \mathrm{~Nm}^{-2}$$ and the height difference is 10 cm . The value of $$\rho$$ is (Acceleration due to gravity $$=10 \mathrm{~ms}^{-2}$$)
Statement (A) When the temperature increases the viscosity of gases increases and the viscosity of liquids decreases.
Statement (B) Water does not wet an oily glass because cohesive force of oil is less than that of water.
Statement (C) A liquid will wet a surface of a solid, if the angle of contact is greater than $$90^{\circ}$$.
What causes the free surface of a liquid to have minimum area?
Assertion (A) The upper surface of the wing of an aeroplane is made convex and the lower surface is made concave.
Reason (R) The air currents at the top have smaller velocity and thus less pressure at the bottom than at the top.
A glass flask weighting 390 g, having internal volume 500 cc just floats when half of it is filled with water. Specific gravity of the glass is
Water does not wet an oily glass because
Identify the incorrect statement regarding Reynold's number $$\left(R_e\right)$$.
The lower end of a capillary tube is dipped into water and it is observed that the water in capillary tube rises by 7.5 cm. Find the radius of the capillary tube used, if surface tension of water is 7.5 $$\times$$ 10$$^{-2}$$ Nm$$^{-1}$$. Angle of contact between water and glass is 0$$\Upsilon$$ and acceleration due to gravity is 10 ms$$^{-2}$$.
An ideal liquid flows through a horizontal tube of variable diameter. The pressure is lowest where the