Terminal Velocity

Q. the pressure of water in a water pipe when tap is opened and closed is respectively 3 * 10^5 N/m^2 and 3.5 * 10^5 N/m^2. With open tap, the velocity of water flowing is

Q.

An air bubble of diameter 2 mm rises steadily through a solution of density 1750 kg m^-3 at the rate of 0.35 cm s^-1. Calculate the coefficient of viscosity of the solution. The density of air is negligible.

1. 11 poise

2. 13.6 poise

3. 2.6 poise

4. 8 poise

Q.

If n identical water droplets falling under gravity with terminal velocity v coalesce to form a single drop which has the terminal velocity 4v. Find the number n.

1. 4

2. 2

3. 6

4. None of these

Q. 67. Water is flowing through a horizontal pipe of non uniform cross section.The speed of water is 30cm/sec at a place where pressure is 10cm .Calculate the speed of water at the other place where the pressure is half of that at the first place

Q. Water is flowing through a horizontal pipe of varying cross-section. At any two places, the diameters of the tube are 4 cm and 2 cm.If the pressure difference between these two places be equal to 4.5 cm(water) , then determine the rate of flow of water in the tube.

Q. In which one of the following cases will the liquid flow in a pipe be most streamlined?

1. Liquid of high viscosity and high density flowing through a pipe of small radius
2. Liquid of high viscosity and low density flowing through a pipe of small radius
3. Liquid of low viscosity and low density flowing through a pipe of large radius
4. Liquid of low viscosity and high density flowing through a pipe of large radius

Q. 46.A Solid ball of density half that of water is dropped at t = 0 from a height of 20 m from the surface of water in a large and deep tank . It falls freely under gravity, then enters into water and then again reaches the water surface .The total time taken in this event is ( neglect viscosity of water and take g =10)

Q. A river 500 m wide is flowing at rate of 4 m/s. A boat is sailing at velocity of 10 m/s with respect to the water. In direction perpendicular to the river flow.The time taken by boat to reach the opposite bank

Q.

A ball of radius r and density $\rho$ falls freely under gravity through a distance h before entering water. Velocity of ball does not change even on entering water. If viscosity of water is n, the value of h is given by

1. 

2. 

3. 

4. 

Q.

A solid sphere falls with a terminal velocity of 20 m s^-1 in air. If it is allowed to fall in vacuum,

1. Terminal velocity will be 20 ms^-1

2. Terminal velocity will be less than 20 m s^-1

3. Terminal velocity will be more than 20 m s^-1

4. There will be no terminal velocity

Q. the rate of steady flow of a liquid through a capillary tube is V under pressure difference P.this tube is connected with another tube of the same length but half radius in series.find the rate of flow through combination if same pressure difference is maintained across the combination.

Q. 26.In van der wal force equation. What is the dimension of a and b ?

Q.

An air bubble of radius 5mm rises through a vat of syrup at a steady speed of 4mm/s. If the syrup has a density of $1.4\times {10}^{3}kg/m^3$, what is its viscosity?

1. 1.15 kg/m-s

2. 15kg/m-s

3. 2.25 kg/m-s

4. 19.05 kg/m-s

Q. A marble of mass $x$ and diameter $2r$ is gently released in a tall cylinder containing honey. If the marble displaces mass $y(<x)$ of the liquid, then the terminal velocity is proportional to

1. $x+y$
2. $x-y$
3. $\frac{x+y}{r}$
4. $\frac{x-y}{r}$

Q. When a small drop of water falls through a large height in the air, the final velocity is independent of the height it starts from.

1. False
2. True

Q. A $50\text{kg}$ skydiver falls through the air and attains terminal velocity after some time. The drag force is a function of velocity given as $F_{\text{drag}}=-b{v}^2$ where the negative sign denotes that the drag force is opposite to the direction of velocity. What is the terminal velocity of the skydiver (assuming the drag constant $b$ is $0.2\text{kg/m})$?

1. $250\text{m/s}$
2. $100\text{m/s}$
3. $5\text{m/s}$
4. $50\text{m/s}$

Q. A spherical ball is dropped in a long column of a viscous liquid. The speed of the ball as a function of time may be best represented by the graph
(a) A
(b) B
(c) C
(d) D

Q. the velocities of A and B are\xrightarrow[v_a]{}=2icap++4jcap and \xrightarrow[v_b]{} =3icap-7jcap.velocity of B as observed by A i

Q. A small sphere initially at rest, falls in to a viscous liquid. Due to drag, heat is produced. Then the relation between rate of production of heat and the radius of the sphere at terminal velocity, is best represented by:

1. $\propto r^2$
2. $\propto r^5$
3. $\propto r^6$
4. $\propto r^3$

Q. A solid sphere falls with a terminal velocity of $20{\text{ms}}^{-1}$ in air. If it is allowed to fall in vacuum.

1. Terminal velocity will be $20{\text{ms}}^{-1}$
2. Teminal velocity will be less than $20{\text{ms}}^{-1}$
3. Terminal velocity will be greater than $20{\text{ms}}^{-1}$
4. No terminal velocity will be attained

Q. Two uniform spherical balls of the same density and radii $r$ and $2r$ are dropped in air and are falling vertically downward. If the terminal velocity of the ball of radius $r$ is $1\text{cm/s}$, then the terminal velocity of the ball of radius $2r$ will be

1. $1\text{cm/s}$
2. $4\text{cm/s}$
3. $3\text{cm/s}$
4. $2\text{cm/s}$

Q. A spherical ball of radius $5\text{mm}$ flowing through the glycerin as shown in figure. The velocity of ball at a particular instant is $0.6\text{m/s}$. Find the drag force on the ball due to the fluid. Assume that Stoke's law is valid. (Take viscosity of glycerine as $0.950\text{kg/m-s}$)

1. $0.026\text{N}$
2. $0.088\text{N}$
3. $0.107\text{N}$
4. $0.053\text{N}$

Q. Eight small drops of equal size are falling through air with a steady velocity of $10\text{cm/sec}$. If the drops coalesce, what would be the terminal velocity of the bigger drop?

1. $40\text{cm/s}$
2. $20\text{cm/s}$
3. $30\text{cm/s}$
4. $50\text{cm/s}$

Q. 33.What does this statement mean area under N-V curve and the velocity axis represents the total no. of molecules

Q. Water flows through a horizontal pipe of varying cross-section at the rate of 1/2 litre/second. Determine the velocity of flow of water at a point where diameter is 4 cm.

Q. In Millikan’s oil drop experiment, what is the terminal speed of an uncharged drop of radius 2.0 × 10¯⁵ m and density 1.2 × 103 kg m¯³. Take the viscosity of air at the temperature of the experiment to be 1.8 × 10¯⁵ Pa s. How much is the viscous force on the drop at that speed ? Neglect buoyancy of the drop due to air.

Q. 20.A body of density d1is counterpoised by Mg of weights of density d2 in air of density d. Then the true mass of the body is

Q. In which one of the following cases will the liquid flow in a pipe be most streamlined

1. Liquid of low viscosity and high density flowing through a pipe of large radius
2. Liquid of high viscosity and high density flowing through a pipe of small radius
3. Liquid of low viscosity and low density flowing through a pipe of large radius
4. Liquid of high viscosity and low density flowing through a pipe of small radius

Q. The relative velocity of two consecutive water layers is 8cm/s and the perpendicular distance between the layers is 0.1cm. The velocity gradient is?

Q.

Water is flowing through a pipe under constant pressure. At some place the pipe becomes narrow. The pressure of water at this place:

1. decreases

2. remains the same

3. depends on several factors

4. increases