Monday 21 September 2015

Viscosity

Multiple choice questions on VISCOSITY 

1) For streamline flow Reynolds number is      
       a) Less than 1100       b) greater than 2100    c) between 1100 to 2100              d) none of these
2) For turbulent flow Reynolds number is
      a) Less than 1100     b) greater than 2100    c) between 1100 to 2100                   d) none of these
3) A free falling object achieves terminal velocity if
    a) Down word force of gravity acting on it equals the up word force of drag experienced by it
    b) Down word force of gravity acting on it less than the up word force of drag experienced by it
    C) Down word force of gravity acting on it greater than the up word force of drag experienced by it
    d) None of these
4) Milliken’s oil drop method used for determination of charge of an electron make use of
    a) Stokes law         b) Hooks law      c) Reynolds law                 d) none of these
5) Settlement of fine particles in water make use of
     a) Stokes law        b) Hooks law      c) Reynolds law             d) none of these
6) ……….   Law can be used to explain as to why do small water droplets remain suspended in air until they grow to a critical size and start falling as rain
        a) Stokes law      b) Hooks law     c) Reynolds law          d) none of these
7) SI unit of coefficient of viscosity is
      a) dyne-s/cm2          b) Ns/m2                c) N/sm2             d) N m2    
8) CGS unit of coefficient of viscosity is
      a) dyne-s/cm2          b) Ns/m2                c) N/sm2             d) N m2   
9) The critical velocity of a liquid is
       a) ῃR / rd                        b) ῃ /R rd          c) Rrd/ῃ               d) Rd/ῃr
10) By Archimedes’ principle buoyancy means
      a) Up word thrust is equals to the loss of weight of body in liquid 
      b) Up word thrust is great than to the loss of weight of body in liquid             
     c) Up word thrust is less than to the loss of weight of body in liquid      
     d) None of these
11) In streamline flow
      a) All liquid molecules do not move in the same direction
      b) All liquid molecules move in the same direction
      c) Some liquid molecules do not move in the same direction
     d) None of these
12) In turbulent flow
     a) All liquid molecules do not move in the same direction
     b) All liquid molecules move in the same direction
    c) Some liquid molecules do not move in the same direction
     d) None of these
13) In the stream line flow
     a) The velocity of fluid is less than the critical velocity
     b) The velocity of fluid is equal to the critical velocity                         
     c) The velocity of fluid is greater than the critical velocity
    d) None of these
14) In the turbulent flow
     a) The velocity of fluid is less than the critical velocity
     b) The velocity of fluid is equal to the critical velocity                         
     c) The velocity of fluid is greater than the critical velocity
    d) None of these
15) The constant maximum velocity of a body moving relative to a fluid such that the resultant force acting on it is zero
       a) Critical velocity                       b) Terminal velocity                      c) Zero velocity                d) None of these
16) The velocity gradient is
       a) dx/dv                       b) dv/dx               c) dv/dt               d) None of above
17) The force of viscosity depends on
     a) Area of surface in contact    b) velocity gradient     c) Nature and temperature of liquid    d) All of these
18) Which of the following fluid is more viscous
    a) Water                   b) kerosene            c) glycerin            d) none of these
18) Which of the following fluid is less viscous
        a) Kerosene       b) paint      c) glycerin       d) honey
19) The viscosity of a liquid decreases rapidly with
     a) An increase in temperature   b) Decrease in temperature   c) Decrease in pressure   d) An increase in pressure
20) The viscosity of a gases increases rapidly with
     a) An increase in temperature   b) Decrease in temperature     c) Decrease in pressure   d) An increase in pressure

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