Which of the following is the correct form of Stoke’s law?
a) CD = 24 / NRe
b) CD = 24 * NRe
c) CD = 18 / NRe
d) CD = 18 * NRe
Q.2.
What is the value of CD corresponding to a Reynold’s number between 5 and 1000?
a) 0.3
b) 0.4
c) 0.2
d) 0.1
Q.3.
Under which condition, is the Cunningham correction factor applicable for very small particles?
a) When particle size is far greater than the gas mean free path
b) When particle size is far lesser than the gas mean free path
c) When particle size becomes comparable to the gas mean free path
d) Cunningham factor is applicable for small particles under all conditions
Q.4.
Under which circumstances is the Oseen formula valid for drag coefficient?
a) When the Reynolds number is between 0.3 and 5
b) When the Reynolds number is between 0.2 and 4
c) When the Reynolds number is between 0.3 and 4
d) When the Reynolds number is between 0.2 and 5
Q.5.
The total drag is a sum of the skin drag and the pressure drag. Which among of the following options, states the correct formula for skin drag and pressure drag?
a) 2πµDU, 2πµDU
b) 1πµDU, 2πµDU
c) 2πµDU, πµDU
d) 3πµDU, πµDU
Q.6.
What are the dimensions of drag coefficient?
a) Dimensionless
b) MLT-2
c) ML-3
d) L
Q.7.
Let FG be the gravitational force, FD be the drag force and FB be the buoyant force. Which of the following best describes the relation between these forces when a sphere falls into a fluid with terminal velocity?
a) FG + FD = FB
b) FG + 2FB = FD
c) 2FB + FD = FG
d) FB + FD = FG
Q.8.
Calculate the drag force on a ball of diameter of 80mm, flowing through air. The density of air is 1.kg/m3 and the ball flows with a velocity of 7m/s. The Reynolds number is 3730.
a) 0.077 N
b) 76969 N
c) 0.011 N
d) 10995 N
Q.9.
Which component of the total force is perpendicular to the direction of motion? What are the dimensions of this component?
a) Lift, MLT-1
b) Drag MLT
c) Drag, MLT-2
d) Lift, MLT-2
Q.10.
Select the incorrect statement.
a) Drag depends inversely on mass
b) Drag is independent of shape
c) Drag linearly depends on velocity
d) Drag depends on compressibility
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