ECAT Pre General Science Physics Chapter 6 Fluid Dynamics Online Test With Answers

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ECAT Pre General Science Physics Chapter 6 Fluid Dynamics Online Test

Sr. # Questions Answers Choice
1 In a _____ flow, each particle of the fluid is called a streamline and different streamlines ______cross each other. Streamline, cannot Turbulent, cannot Streamline, can None of these
2 The study of fluid in motion basically involves law of conservation of: Mass Energy Change Both A and C Both A and B
3 The drag force acting on a spherical droplet of radius 10-5m moving with a velocity of 1 cm/sec in a fluid of velocity 5.31 x 10-7m/sec. The units comes out to be: 10<sup>-16</sup>N 10<sup>-14</sup>N 10<sup>-12</sup>N 10<sup>-10</sup>N
4 The dimensions of viscosity are: M<sup>2</sup>L<sup>-1</sup>T<sup>-2</sup> M<sup>-1</sup>L<sup>1</sup>T<sup>-1</sup> M<sup>-1</sup>L<sup>-1</sup>T ML<sup>-1</sup>T<sup>-1</sup>
5 The unit of viscosity is SI system is: Kg<sup>-1</sup>m sec<sup>-1</sup> Kgm<sup>-1</sup> sec<sup>-1</sup> Kg<sup>-1</sup>m<sup>-1</sup> sec None of these
6 When the upward drag force of the fluid becomes equal to downward force of gravity of the droplet, then its velocity: Starts increasing Starts decreasing Becomes constant Is called escape velocity
7 0.10 cm can be written as: 1.0 x 10<sup>-2</sup>m 1.0 x 10<sup>-3</sup>cm 1.0 x 10<sup>-4</sup>cm 1. x 10<sup>-4</sup>m
8 Stoke;s law is not applicable when the speed of the object moving through a fluid is: Zero Small Large None of these
9 Drag force increases if speed of the object moving through the fluid: Increases Decreases Remains constant None of these
10 Fog droplets are suspended in air when their weight is balanced by: Force of gravity Upward trust due to air Surface tension None of these
11 At high speed, fluid friction _____ and fuel consumption ___,: Increases, decreases Increases, increases Decreases, increases None of these
12 Two copper balls of 1 cm and 2 cm in diameter are simultaneously dropped in the same viscous medium. The terminal velocity of bigger ball is: Not affected due to its size Twice that of small size ball Four times that of small size ball 1/4th of that of small size ball
13 When the droplet moves with terminal velocity in a fluid, the net force acting on the droplet is: F<sub>D</sub>-mg Zero mg-F<sub>D</sub> None of these
14 The _____ viscous the medium is _____, is the value of terminal velocity of the droplet: More, lesser Lesser, more Both A and B Lesser, lesser
15 Terminal velocity is the maximum velocity attained by a spherical droplet when the drag force______the weight of droplet: Is smaller than Is greater than Becomes equal to None of these
16 A massive object falls through a fluid: Faster Slower Slowest None
17 High speed meteors rushing through air reduces to ashes because of: Force of gravity High resistance of air Drag force None of these
18 Stock's law holds for: Motion through free space Motion through viscous medium Bodies of all shapes None of these
19 Viscosity of water is ______ that of air but ___ that of plasma. More, more Less, more Less, less More, less
20 Fluid friction is _____ the friction between two solid surfaces: Greater than Smaller than Equal to None of these
21 Density of fluid is defined as: Its volume to mass ratio Product of volume and mass Its mass of volume ratio None of these
22 Unit of viscosity is: Kg m<sup>-1</sup>sec<sup>-1</sup> N s m<sup>-2</sup> J s m<sup>-3</sup> All of these
23 Glycerin has viscosity _____ the viscosity of water: More than Equal to Less than None of these
24 A body is moving through a viscous medium eventually comes to rest because of: Force of gravity Force of friction Its weight Both A and C
25 N s m-2is unit of: Drag force Pressure Surface tension Coefficient of viscosity
26 Machine parts are jammed due to: Increasing in viscosity of lubricant Decreasing in viscosity of lubricant Decreasing in surface tension of lubricant None of these
27 The body passing a viscous medium affected by: One force only Two forces only Four forces None of these
28 The resistance offered by a fluid to a solid moving inside it is called: Drag force Surface force Viscosity None of these
29 The property of fluids due to which they resist their own flow is called: Drag force Surface tension Viscosity None of these
30 A tube is tapered from 20 cm diameter to 2 cm diameter, the velocity at the first cross-section is 50 cm/s, then the velocity at the second cross-section is 50 m/s 20 m/s 40 cm/s 5 cm/s
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