# Thermal boundary layer is a region where

1.  Inertia terms are of the same order of magnitude as convection terms

2.  Convection terms are of the same order of magnitude as dissipation terms

3.  Convection terms are of the same order of magnitude as conduction terms

4.  Dissipation is negligible

4

Dissipation is negligible

Explanation :
No Explanation available for this question

# The thickness of thermal and hydrodynamic boundary layer is equal if (Pr = Prandlt Number, Nu = Nusselt Number)

1.  Pr = 1

2.  Pr > 1

3.  Pr < 1

4.  Pr = Nu

4

Pr = 1

Explanation :
No Explanation available for this question

# The temperature distribution at a certain instant of time in a concrete slab during curing is given by, T = 3x2 + 3x + 16, where x is in cm and T is in K. The rate of change of temperature with time is given by (assume diffusivity to be 0.0003 cm2/s)

1.  + 0.0009 K/s

2.  + 0.0048 K/s

3.  - 0.0012 K/s

4.  - 0.0018 K/s

4

- 0.0018 K/s

Explanation :
No Explanation available for this question

# The transition Reynolds number for flow over a flat plate is 5 * 105. What is the distance from the leading edge at which transition will occur for flow of water with a uniform velocity of 1 m/s [For water the kinematic viscosity v = 0.858 * 10-6 m2/s]

1.  1 m

2.  0.43 m

3.  43 m

4.  103 m

4

0.43 m

Explanation :
No Explanation available for this question

# The ratio of the thickness of thermal boundary layer to the thickness of hydrodynamic boundary layer is equal to (Prandtl Number)n, where n is

1.  - 1/3

2.  - 2/3

3.  1

4.  - 1

4

- 1/3

Explanation :
No Explanation available for this question

# Water jacketed copper rod D m in diameter is used to carry the current. The water which flows continuously maintains the rod temperature at T1 0C during normal operation at 1 amps. Electrical resistance of the rod is known to be “R” Ω/m. If the coolant water ceased to be available and the heat removal diminished greatly, the rod would eventually melt. What is the time required for melting to occur if the melting point of the rod material is Tmp [Cp = specific heat, ρ = density of the rod material and L = length of the rod]

1.  [Ρ (πD2/4) Cp (Tmp – T1)]/I2R

2.  (Tmp – T1)/PI2R

3.  Ρ (Tmp – T1)/I2

4.  Cp (Tmp – T1)/I2R

4

[Ρ (πD2/4) Cp (Tmp – T1)]/I2R

Explanation :
No Explanation available for this question

# In a shaping process, the number of double strokes per minute is 30 and the quick return ratio is 0.6. If the length of the stroke is 250mm, the average cutting velocity in mm/min is

1.  3.0

2.  4.5

3.  7.5

4.  12.0

4

12.0

Explanation :
No Explanation available for this question

# For wire drawing operation, the work material should essentially be

1.  ductile

2.  tough

3.  hard

4.  malleable

4

ductile

Explanation :
No Explanation available for this question

# The maximum allowable compressive stress corresponding to lateral bucking in a discretely laterally supported symmetrical I-beam, does not depend upon

1.  Modulus of elasticity

3.  Span/length of the beam

4.  Ratio of overall depth to thickness of the flange

4

Modulus of elasticity

Explanation :
No Explanation available for this question

1.  0.307

2.  0.5

3.  0.693

4.  1.0

4