Free Fluid Drag MCQs with Answers

• A. the square of the speed
• B. the speed
• C. the cube of the radius
• D. the inverse of the radius

Explanation: Stokes's law gives the drag as 6 pi eta r v, so it rises in direct proportion to both the radius and the speed, provided the flow stays…

• A. N s per m squared
• B. N per m squared
• C. N m
• D. m squared per s

Explanation: Viscosity is defined through the relation between shear stress and velocity gradient, giving units of newton second per square metre…

• A. increases
• B. decreases
• C. stays the same
• D. becomes zero

Explanation: Heating gives the molecules enough energy to slip past one another more easily, weakening the intermolecular attractions that resist flow…

• A. Rough
• B. Square
• C. Circular
• D. Spherical

Explanation: Stokes' law applies to a small spherical body moving slowly through a viscous fluid, where the drag force is F = 6π η r v.

• A. The shinning side of the ball
• B. Rough side
• C. The seam of the ball
• D. Goes straight

Explanation: In reverse swing, the ball moves towards its shiny side because the airflow and boundary-layer separation around an old, fast-moving ball…

• A. Newtons law
• B. Pascals law
• C. Gauss law
• D. Stokes law

Explanation: For a small sphere moving slowly through a viscous fluid, Stokes' law gives drag force F = 6π η r v, where F is in N, η in Pa·s, r in m…

• A. ML-1T-1
• B. M2L1T1
• C. ML1T-1
• D. M2L-1T-1

Explanation: The coefficient of viscosity is obtained from viscous force divided by velocity gradient and area: η = F/(A × velocity gradient), giving…

• A. Kg.m.S-1
• B. Kg m-1.S-1
• C. Kg.m.S
• D. Kg-1.m-1.S-1

Explanation: From viscous force F = ηAv/l, η = Fl/(Av), giving units kg m s^-2 × m divided by m² × m s^-1 = kg m^-1 s^-1.

• A. Force
• B. Pressure
• C. Momentum
• D. Energy

Explanation: Pressure is force per unit area, so its dimensions are (MLT^-2)/L² = ML^-1T^-2.

• A. 1 N
• B. 10 N
• C. 100 N
• D. none

Explanation: The force needed to stop a normally striking water jet is F = ρQv = (1000 kg/m^3)(0.0001 m^3/s)(10 m/s) = 1 kg m/s^2 = 1 N, so option a is…

• A. F / 4
• B. F / 2
• C. F
• D. 2F

Explanation: In fluid dynamics, the drag force on an object moving through a fluid is typically proportional to the square of the velocity of the…

• A. Increases
• B. Decreases
• C. Remains constant
• D. Both B and C

Explanation: Drag force is a resistive force, which can only increase as forward force increases.

• A. r = √qvt / 2ρg
• B. r2 = 9ηvt / ρg
• C. r2 = 9ηvt / 2ρg
• D. r = 9ηvt / 2ρg

Explanation: Explanation If ρ is the density of the droplets then its volune can be expressed as: V = 4/3 πr³As, ρ = m / VSo, ρ = m / (4/3 πr³ρ) m =…

• A. 500 Km min-1
• B. 500 Km sec-1
• C. 1000 Km h-1
• D. 500 Km h-1

Explanation: Explanation:The lifting of a bullet train above the rails due to magnetic fields reduces friction, allowing the train to reach higher…

• A. F = 6πηrv
• B. F = (4/3)πr3ρg
• C. F = 6πηr2ρ
• D. F = 2gr2ρ/9η

Explanation: Stokes' Law describes the drag force experienced by a small spherical object moving through a fluid at a low velocity.

• A. Velocity
• B. Viscosity of fluid
• C. Density of the body
• D. All of above

Explanation: When a body falls through a fluid, it experiences a resistance force due to the viscosity of the fluid.

• A. Spherical shape
• B. Oblong shape
• C. Rectangular shape
• D. Curve shape

Explanation: Stokes' Law holds true for bodies that have a spherical shape. It describes the motion of a small spherical particle through a viscous…