In which of the following the friction drag is generally larger than pressure drag?

Related Mcqs:

1. If a sphere of diameter 1 cm falls in castor oil of kinematic viscosity 10 stokes, with a terminal velocity of 1.5 cm/sec, the coefficient of drag on the sphere is________________?

   A. less than 1
   B. between 1 and 100
   C. 160
   D. 200

2. Drag force is a function of________________?

   1. projected area of the body
   2. mass density of the fluid
   3. velocity of the body
   The correct answer is ?

   A. (1) and (2)
   B. (1) and (3)
   C. (2) and (3)
   D. (1), (2) and (3)

3. With the same cross-sectional area and immersed in same turbulent flow, the largest total drag will be on__________________?

   A. a circular disc of plate held normal to flow
   B. a sphere
   C. a cylinder
   D. a streamlined body

4. The value of friction factor ‘f’ for smooth pipes for Reynolds number 106 is approximately equal to________________?

   A. 0.1
   B. 0.01
   C. 0.001
   D. 0.0001

5. The horse power transmitted through a pipe is maximum when the ratio of loss of head due to friction and total head supplied is________________?

   A. 1/3
   B. 1/4
   C. 1/2
   D. 2/3

6. For laminar flow in circular pipes, the Darcy’s friction factor f is equal to_________________?

   A. 16/Re
   B. 32/ Re
   C. 64/ Re
   D. none of the above where R,, is Reynolds number

7. For laminar flow in a pipe of circular cross-section, the Darcy’s friction factor f is________________?

   A. directly proportional to Reynolds number and independent of pipe wall roughness
   B. directly proportional to pipe wall roughness and independent of Reynolds number
   C. inversely proportional to Reynolds number and indpendent of pipe wall roughness
   D. inversely proportional to Reynolds number and directly proportional to pipe wall roughness

8. For hydro-dynamically smooth boundary, the friction coefficient for turbulent flow is_______________?

   A. constant
   B. dependent only on Reynolds number
   C. a function of Reynolds number and relative roughness
   D. dependent on relative roughness only

9. The total pressure on a plane surface inclined at an angle 9 with the horizontal is equal to_______________?

   A. PA
   B. pA sin 9
   C. pA cos 9
   D. pA tan 9

   where p is pressure intensity at centroid of area and A is area of plane surface

10. The speed of a pressure wave through a pipe depends upon________________?

    A. the length of pipe
    B. the viscosity of fluid
    C. the bulk modulus for the fluid
    D. the original head