Free Fluid Flow MCQs with Answers

• A. the fluid particles move in irregular, mixing paths
• B. each fluid particle follows the same smooth path as the one before it
• C. the fluid is at rest
• D. the fluid is compressible

Explanation: In laminar or streamline flow the layers slide over one another without mixing, so the velocity at any fixed point stays constant in time…

• A. the weight of the body
• B. the weight of the fluid displaced by the body
• C. the volume of the body
• D. the density of the fluid

Explanation: This is Archimedes's principle, and the upthrust arises because pressure increases with depth, so the upward force on the bottom of the…

• A. the speed falls below a critical value
• B. the speed exceeds a critical value and the Reynolds number becomes large
• C. the pipe is perfectly smooth
• D. the fluid is very viscous

Explanation: Turbulence sets in when inertial effects dominate viscous ones, which is what a large Reynolds number expresses, and it appears as eddies…

• A. Slightly less than critical velocity
• B. Equal to critical velocity
• C. Greater than critical velocity
• D. Increasing gradually but less than critical velocity

Explanation: Below the critical velocity the flow stays in orderly layers, and only once that threshold is passed does the motion break up into eddies…

• A. Different in different direction
• B. Same in all direction
• C. Same only along opposite directions
• D. Same only along normal directions

Explanation: Pascal's law states that pressure applied to an enclosed fluid is transmitted equally in all directions.

• A. MLT
• B. ML-1T-1
• C. ML-1T-2
• D. ML-2T-2

Explanation: Pressure is force per unit area, so its dimensions are [P] = [F]/[A] = (MLT^-2)/L^2 = ML^-1T^-2.

• A. Laminar
• B. Streamline
• C. Turbulent
• D. Both A and B

Explanation: Turbulent flow contains irregular eddies, so the motion of individual fluid particles is difficult to follow or predict.

• A. 120 to 80 torr
• B. 100 to 80 torr
• C. 120 to 60 torr
• D. 60 to 140 torr

Explanation: A commonly quoted normal blood pressure is about 120 torr systolic over 80 torr diastolic, written as 120/80 torr.

• A. Water
• B. Honey
• C. Mercury
• D. Oil (kerosene)

Explanation: Human blood has a density of approximately 1.06 x 10^3 kg m^-3, which is close to water's density of about 1.00 x 10^3 kg m^-3.

• A. Laminar
• B. Turbulent
• C. Mixed
• D. None

Explanation: Blood normally flows in an orderly, layered manner through arteries, which is laminar flow, including under ordinary systolic conditions.

• A. Low
• B. High
• C. Very high
• D. Some time high and some time low

Explanation: Laminar flow is favoured when the fluid speed is low, because viscous forces can keep neighbouring layers moving smoothly.

• A. Venturimeter
• B. Blood pressure
• C. Sphygmomanometer
• D. Sonometer

Explanation: A sphygmomanometer is the instrument used to measure arterial blood pressure, normally reporting systolic and diastolic pressures in torr…

• A. Low blood pressure
• B. High blood pressure
• C. Normal blood pressure
• D. Abnormal blood pressure

Explanation: Systolic pressure is the maximum arterial pressure reached when the ventricles contract, so it is the higher of the two blood-pressure…

• A. Standing straight
• B. Sitting on chair
• C. Sitting on ground
• D. Laying horizontally

Explanation: When a person lies horizontally, the vertical height difference between the head and feet is smallest, so the hydrostatic pressure…

• A. On the train
• B. Away from the train
• C. Towards the train
• D. On himself

Explanation: Air moves rapidly in the narrow region beside the train, so Bernoulli's principle gives lower pressure there than on the other side of the…

• A. Rigid
• B. Not rigid
• C. Of glass
• D. Of rubber

Explanation: Blood vessels are elastic and deformable rather than rigid, allowing their diameter to change with blood pressure and flow.

• A. Streamline
• B. Turbulent
• C. Uniform
• D. Laminar

Explanation: Irregular flow with eddies and rapidly changing velocity is called turbulent flow.

• A. The velocity of the fluid is constant
• B. The flow of the fluid is the straight line
• C. The density of the fluid is constant
• D. The volume of the fluid is constant

Explanation: An incompressible fluid has constant density, meaning its mass per unit volume does not change appreciably under the conditions…

• A. Turbulent
• B. Streamline
• C. Irregular
• D. Straight line

Explanation: An ideal fluid is treated as non-viscous and incompressible, and elementary fluid mechanics commonly considers its flow along smooth…

• A. Different in different direction
• B. Same in all direction
• C. Same only along opposite directions
• D. Same only along normal directions

Explanation: Pascal's law states that in a confined fluid, pressure is transmitted equally in all directions.