QUIZ : CIVIL ENGINEERING (01-09-2020)

Quiz: Civil Engineering
Exam: SSC-JE
Topic: Hydraulics & Fluid Mechanics

Each question carries 1 mark
Negative marking: 1/4 mark
Time: 10 Minutes

Q1. Mixing of milk with water is due to
(a) very good cohesion
(b) very good adhesion
(c) very good surface tension
(d) very good vapour pressure

Q2. If angle of contact of a drop of liquid is acute then
(a) adhesion is more than cohesion
(b) cohesion is more than adhesion
(c) cohesion is equal to adhesion
(d) adhesion and cohesion have no bearing with angle of contact

Q3. The center of pressure of a surface subject to fluid pressure is the point
(a) on the surface at which resultant pressure acts
(b) on the surface at which gravitational force acts
(c) at which all hydraulic forces meet
(d) similar to metacenter

Q4. If a Mohr’s circle is drawn for a fluid element inside a fluid body at rest, it would be
(a) a circle touching the origin
(b) a circle not touching the origin
(c) a point on the shear stress axis
(d) a point on the normal stress axis

Q5. The position of centre of pressure on a plane surface immersed vertically in a static mass of fluid is
(a) at the centre of pressure on a plane surface immersed vertically in a static mass of fluid is
(b) always above the centroid of the area
(c) always below the centroid of the area
(d) none of the above

Q6. The horizontal component of force on a curved surface is equal to the
(a) product of pressure intensity at its centroid and area
(b) force on a vertical projection of the curved surface
(c) weight of liquid vertically above the curved surface
(d) force on the horizontal projection of the curved surface

Q7. A circular plate of diameter d is submerged in water vertically, so that the topmost point is just at the water surface. The centre of pressure on the plate will be below the water surface at a depth of
(a) 5d/8
(b) 2d/3
(c) 11d/16
(d) 3d/4

Q8. The vertical distance of the centre of pressure below the centroid of the inclined plane area is
(a) I_c/(Ay_c )
(b) (I_c sin^2⁡θ)/(Ah_c )
(c) (I_c Sin^2 θ)/(Ay_c )
(d) (I_c sinθ)/(Ay_c )

Q9. The Centre of gravity of the volume of liquid displaced is called
(a) Centre of pressure
(b) centre of buoyancy
(c) metacentre
(d) none of these

Q10. When a block of ice floating on water in a container melts, the level of water in the container
(a) rises
(b) first falls and then rises
(c) remains the same
(d) falls

Solutions

S1. Ans.(b)
Sol. Mixing of milk with water is very good adhesion.

S2. Ans.(a)
Sol. When adhesion force is more than cohesion force then fluid will wet the surface and angle of contact between fluid and surface will be acute.

S3. Ans.(a)
Sol. Centre of Pressure is defined as the point of application of the total pressure on the surface.

S4. Ans.(d)
Sol. If a Mohr’s Circle drawn for a fluid element inside a fluid body at rest, it would be a point on the normal stress axis.

S5. Ans.(c)

S6. Ans.(b)
Sol. The horizontal component of force on a curved surface is equal to the force on a vertical projection of the curved surface.

S7. Ans.(a)
Sol. h_p = h_c+I_gg/(Ah_c )
= d/2+(π/64 d^4)/(π/4 d^2 × d/2)
= d/2+d/8
= 5d/8

S8. Ans.(b)
Sol. Vertical distance of the centre of pressure below the centroid of the inclined plane area
= (I_gxx sin^2⁡θ)/(h ̅A)

S9. Ans.(b)
Sol. The centre of gravity of the volume of liquid displaced is called centre of buoyancy.

S10. Ans.(c)

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