# Mechanical Properties of Fluids Multiple Choice Questions

Q1. What is the dimensional formula for pressure?

1. [MLT-1]
2. [ML-1T-2]
3. [ML-1T-3]
4. [M2L-1T-2]

Q2. Which of the following factor will not affect the value of angle of contact?

1. Cleanliness of the surface in contact
2. Medium above the free surface of the liquid
3. Temperature of the liquid
4. Pressure of the liquid

Q3. In case of streamlined flow of liquid, the loss of energy is

1. minimum
2. maximum
3. zero
4. infinite

Q4. If the surface of a liquid is plane, then the angle of contact of the liquid with the walls of container is

1.  0°
2. Obtuse angle
3.  Acute angle
4.   90°

Q5. Viscosity is the property of fluids by virtue of which they tend to:

1. create a relative motion between their layers
2. maintain the relative motion between their layers
3. destroy any relative motion between their layers
4. none of the above

Q6. The speed of efflux from an open tank is given by a formula identical to that of a:

1. projectile
2. recoiling gun
3. freely falling body
4. liquid flowing in a horizontal pipe

Q7. A tank containing water has an orifice on one vertical wall. If the centre of the orifice is 5 m below the surface of water in the tank, the velocity of discharge is (take g = 9.8 m/s2)

1. 10 m/s
2. 9.9 m/s
3. 9.5 m/s
4. 9 m/s

Q8. Fire fighters have a jet attached to the head of their water pipes.  This is done to

1. increase the mass of water flowing out in one second
2. increase the volume of water flowing out in one second
3. increase the velocity of water flowing out in one second
4. none of the above

Q9. Water flows through a horizontal pipe whose internal diameter is 2.0 cm, at a speed of 1.0 ms-1. What should the diameter of the nozzle be, if the water is to emerge at a speed of 4.0 ms-1?

1. 1.5 cm
2. 1.0 cm
3. 4.0 cm
4. 2.0 cm

Q10. Water is flowing through a tube of non-uniform cross-section.  If the ratio of radius of the tube at the entrance and exit is 3 : 2, then the ratio of velocity of liquid entering and leaving the tube is:

1. 8 : 27
2. 4 : 9
3. 1 : 1
4. 9 : 4

Q11. If drops and bubbles do not collapse under the effect of gravity, it indicates that

1. pressure inside the drop is lower than outside it
2. pressure inside the drop is greater than outside
3. Surface tension is low
4. Viscosity is large

Q12. Two light balls are suspended with light strings very close to each other. What happens when we blow air between the balls:

1. They come together
2. They go apart
3. Both of them will move in the same direction in right angle to the speed of air
4. They will be unaffected

Q13.The viscosity of gases ________ with increase in temperature

1. Increase
2. Decrease
3. Remain same
4. Depends on the type of liquid

Q14. Water is flowing through a pipe under constant pressure. At some place the pipe becomes narrow. The pressure of water at this place:

1. increases
2. decreases
3. remains the same
4. depends on several factors

Q15. Water rises to a height of 20 mm in a capillary. If the radius of the capillary is made 1/3 rd of its previous value, to what height will the water now rise in the tube?

1. 80 mm
2. 40 mm
3. 60 mm
4. 30 mm

Q16. A venturimeter is used to

1. find viscosity of a fluid
2. measure speed of a freely falling body in the fluid
3. measure flow speed of incompressible fluid
4. measure atmospheric pressure

Q17. A flat plate is separated from a large plate by a layer of glycerine of thickness 3 X 10-3m.  If the co-efficient of viscocity of glycerine is 2 Nsm2, what is the force required to keep the plate moving with a velocity of 6 X 10-2 m/s. Area of the plate is 4.8 X 10-3m2.

1. 192 N
2. 19.2 N
3. 1.92 N
4. 0.192 N

Q18. Hydraulic brakes use

1. Stoke’s Law
2. Gas Law
3. Pascal’s Law
4. Archimide’s Principle

Q19.The quantity which determines the nature of flow of a viscous liquid through a pipe is known as

1. Viscosity
2. Surface tension
3. Reynold’s number
4. Dynamic lift

Q20. What is torr?

1. Unit to measure surface tension
3. Unit to measure pressure.
4. Unit to measure elasticity

Q21. Pressure inside the constricted artery is

1. lower than external pressure
2. Greater than the external pressure
3. Almost equal to external pressure
4. May be equal or greater than external pressure

Q22. Which of the energy is not related to streamline flow of liquid?

1. Potential Energy
2. Kinetic Energy
3. Pressure Energy
4. Surface Energy

Q23. The terminal velocity of a steel ball of 4 mm in diameter falling through a glycerin of viscosity 3.3 poise, given relative density of steel is 8, relative density of glycerin is 1.3 is

1. 17.47 cm s-1
2. 1.77 cm s-1
3. 1.47 cm s-1
4. 13.23 cm s-1

Q24. As the velocity of a body increases, the viscous force on it

1. Decreases
2. Increases
3. Remains unaltered
4. Might increase or decrease according to medium

Q25. Range of Reynold’s number for the laminar flow of a liquid is

1. Zero to 1000
2. Zero to 2000
3. 1000 to 2000
4. 2000 to 3000

Q26. Pressure in liquids is mathematically expressed as

1. p = hPg
2. p = Pg/h
3. p = hg/P
4. p = hP/g

Q27. Bernoulli’s theorem is applied to:

1. Compressible liquid in streamlined flow
2. Compressible liquid in turbulent flow
3. Incompressible liquid in streamlined flow
4. Incompressible liquid in turbulent flow

Q28. Find the density when a liquid 5 m high in a column exerts a pressure of 80 Pa

1. 1.6 kg/m3
2. 0.625 kg/m3
3. 625 kg/m3
4. 2.625 kg/m3

Q29. Flow of water in hilly area is an example of streamline flow.

1. always true
2. always false
3. True, only if the slope is smooth
4. False, if the slope is not smooth.

Q30. Deep water runs almost still. What does it explain.

1. Magnus effect
2. Equation of continuity
3. Surface energy
4. Bernoulli’s Theorem

Q31.Streamlines are a map depicting fluid flow. Two streamlines do not intersect because

1. Bernoulli’s equation will be violated
2. a fluid particle cannot have two possible velocities at a point
3. it is difficult to draw them in that manner
4. the velocity varies as the fluid flows

Q32. When the velocity of liquids exceed the critical velocity then

1. streamline flow becomes turbulent
2. turbulent flow becomes streamlined
3. turbulent flow becomes smooth
4. streamline flow becomes more smooth

Q33. Bernoulli’s theorem is important in the field of:

1. Photoelectric effect
2. Electrical cells
3. Magnetism
4. Flow of liquids

Q34. A garden sprinkler has 150 small holes, each of 2 mm2 area. If water is supplied at the rate of 0.3 litres/s, then find the average velocity of the spray.

1. 0.1 cm/s
2. 22.5 cm/s
3. 100 cm/s
4. 300 cm/s

Q35. Air is streaming past a horizontal airplane wing such that its speed is 120 m/s over the upper surface and 90 m/s at the lower surface. If the density of the air is 1.3 kg/m3 and the wing is 10 m long and has an average width of 2 m, then the difference of pressure on the two sides of the wing is

1. 4.095 Pa
2. 409.5 Pa
3. 4095.0 Pa
4. 40.95 Pa

Q36. During flight, the weight of the plane is balanced by

1. Gravitational force
2. Dynamic lift provided by wings
3. Magnus effect
4. High speed of plane

Q37. The pressure inside a bubble of radius R and surface tension S is

1. 4S.R
2. 2S/R
3. 4S/R
4. 2S/R

Q38. A person standing near the track of a fast moving train has a tendency to fall towards it because of:

1. Vibration due to motion of train.
2. Gravitational force of attraction between person and train.
3. the high speed of train
4. some other effect.

Q39. The angle of contact for liquid on a solid surface is the angle between:

1. the tangent to the liquid surface at the point of contact and the solid surface
2. the tangent to the solid surface at the point of contact and the liquid surface
3. the liquid surface and the solid surface at the point of contact
4. none of the above.

Q40.The dynamic lift due to spinning is called:

1. Hooke’s law
2. Bernoulli’s theorem
3. Magnus Effect
4. Aerofoil