Reynold's Number
Trending Questions
Q. A particle is moving along the x-axis under the influence of a force given by F = –5x + 15. At t = 0, the particle is located at x = 6 and is having zero velocity. It takes 0.5 seconds to reach the origin for the first time. The equation of motion of particle can be represented by
Q. The Reynolds number of a flow is the ratio of
- Gravity to viscous force
- Gravity force to pressure force
- Inertia force to viscous force
- Viscous forces to pressure forces
Q. Formula of upthrust is vdg. What is g. Is it the acceleration on the object or on the fluid
Q. Two different liquids are flowing in two tubes of equal radius. The ratio of coefficients of viscosity of liquids is 52:49 and the ratio of their densities is 13:1, then the ratio of their critical velocities will be
- 4 : 49
- 49 : 4
- 2 : 7
- 7 : 2
Q.
A rocket of mass 1000 kg exhausts gases at a rate of 4 kg/sec with a velocity 3000 m/s. The thrust developed on the rocket is
12000 N
120 N
800 N
200 N
Q. (a) What is the largest average velocity of blood flow in an artery of radius 2×10¯³m if the flow must remain lanimar? (b) What is the corresponding flow rate ? (Take viscosity of blood to be 2.084 × 10¯³ Pa s).
Q. 74.A block of mass 20 kg is moved with constant velocity along an inclined plane of inclination 37^° with help of a force of constant power 50 W. If the coefficient of kinetic friction between block and surface is 0.25, then what fraction of power is used against gravity? (1) Image not present (2) Image not present (3) Image not present (4) Image not present
Q. A sphere of mass 50 gm and diameter 20 cm rollswithout slipping with a velocity of 5 cm/sec. Itstotal kinetic energy is :-(1) 625 ergs(2) 875 ergs(3) 250 ergs(4) 875 joules
Q. The ratio of terminal velocities of two water drops while falling toward the earth surface is 4:9 . Determine the ratio of their radii.
Q. a container with square base of side a is filled upto a height H with a liquid.a hole is made at a height h from frees surface of water.with what acceleration container must be accelerated so that water doesnt come out? 1.g 2.g/2 3.2gH/2 4.2gh/a
Q. The Reynolds number for laminar flow is
- More than 4000
- More than 2100
- Less than 2100
- Between 2100 and 4000
Q. If a ball of steel (density ρs=7.8 g/cm3) attains a terminal velocity of 10 cm/s when falling in a tank of water (coefficient of viscosity, ηw=8.5×10−4 Pa-s). Then, its terminal velocity in glycerine (ρg=1.2 g/cm3, ηg=13.2 Pa-s) would be nearly:
- 1.5×10−5 cm/s
- 6.45×10−4 cm/s
- 6.25×10−4 cm/s
- 1.6×10−5 cm/s
Q. a thin hollow sphere of mass m is completely filled with a liquid of mass m.when the sphere rolls with a velocity v.kinetic energy of the system is
Q.
Water flows at a speed of 6 cm s-1 through a tube of radius 1 cm. Coefficient of viscosity of water at room temperature is 0.01 poise. Calculate the Reynolds number. Is it a steady flow?
60, no
60, yes
120, no
120, yes
Q. a solid spherical ball is rolling without slipping down an inclined plane . The fraction of its total energy associated with rotation
Q. Explain why a car does not move when the force is applied on it by a person present inside the car?
Q. Two particles move horizontally initially with constant acceleration g. At the start, the particles start moving in opposite direction from the same point with velocities 3 m/s and 4 m/s. The distance between the particles when their velocity vectors are perpendicular is \lbrack g is acceleration due togravity\rbrack (1) 1.5m (2) 2 m (3) 3 m (4) 2.4 m
Q. The motion of a body is given by the equation dv(t)dt=6.0−3v(t). Where v(t) is speed in ms and t in sec. If body was at rest at t = 0
- The terminal speed is
- The speed varies with the time as
- The speed is
when the acceleration is half the initial value
- The magnitude of the initial acceleration is
Q. 63.A solid sphere of radius R made of materials of bulk modulus B surrounded by a piston of area A float on the surface of the liquid. Find the fractional decrease in the radius of the sphere when mass M is placed on the piston
Q. Glycerine flows steadily through a horizontal tube of length 1.5 m and radius 1.0 cm. If the amount of glycerine collected per second at one end is 4.0 × 10¯³ kg s–¯¹, what is the pressure difference between the two ends of the tube ? (Density of glycerine = 1.3 × 103 kg m¯³ and viscosity of glycerine = 0.83 Pa s). [You may also like to check if the assumption of laminar flow in the tube is correct].
Q. In deriving Bernoulli’s equation, we equated the work done on the fluid in the tube to its change in the potential and kinetic energy. (a) What is the largest average velocity of blood flow in an artery of diameter 2 × 10¯³ m if the flow must remain laminar ? (b) Do the dissipative forces become more important as the fluid velocity increases ? Discuss qualitatively.
Q. Which of the following is not the characteristic of turbulent flow
Velocity more than the critical velocity
Velocity less than the critical velocity
- Irregular flow
- Molecules crossing from one layer to another
Q. Calculate Reynold’s number, if a fluid having a viscosity of 0.4 Ns/m2 and density of 900 kg/m3 flows through a pipe of length 20 mm with a velocity of 2.5 m/s.
- 112.5
- 130
- 121.5
- 100
Q. 26 In the situation shown, pulley P is a circular disc having mass 4 kg and it is free to rotate about the
horizontal axis passing through its centre. When the hanging block is released from rest then during its
fall
light string
2 k
(1) Angular velocity of the disc increases at a constante
(2) Rotational kinetic energy of the disc increases at a constant rate
(3) Kinetic energy of the hanging block increases at a
(4) All of these
t rate
Q. A solid spherical ball is rolling with out slipping down an inclined plane.The fraction of its total energy associated with rotation is
Q. A ball falls from a height of 500m how gravity will effect its velocity during its fall.
Q. A solid sphere is rolling ob a frictionless plane surface about its axis of symmetry. Find the rotational energy and the ratio of rotational energy to its total energy
Q. 18. A solid sphere moves at a terminal velocity of }20m/s in air at a place where }g=9.8m/s^2 . The } sphere is taken in a gravity free hall having air at the same pressure and pushed down at a } speed of }20m/s. (A) Its initial acceleration will be }9.8m/s^2 downward } (B) Its initial acceleration will be }9.8m/s^2 upward} (C) The magnitude of acceleration will decrease as the time passes. } (D)It will eventually stop.
Q. A boy sitting in the rear end of the train, running at a constant acceleration on rails, throw a ball towards the fore end of the compartment with a velocity of 20m/s at angle of 370 above the horizontal, when the train is running at speed of 10m/s. If the same boy catches the ball without moving from his seat and at the same height of projection, Find the speed of the train at the instant of his catching the ball.
Q.
The depth x upto which a bullet penetrates in a human body depend on coefficient of elasticity and kinetic energy. Establish the relation between these quantities using the method of dimensions.