During decarburising of a plain carbon steel, the thickness of ferrite layer growth is proportional to

Carbon content in plain carbon steel is __________ percent.

A

0.1 to 0.15

B

0.35 to 0.45

C

0.65 to 0.80

D

0.85 to 1.2

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 equal to

A

$$ - \frac{1}{3}$$

B

$$ - \frac{2}{3}$$

C

1

D

$$-1$$

Routers operate at layer _____. LAN switches operate at layer _____. Ethernet hubs operate at layer _____. Word processing operates at layer _____.

A

3, 3, 1, 7

B

3, 2, 1, none

C

3, 2, 1, 7

D

3, 3, 2, none

E

All of the above

Maximum percentage of carbon in ferrite is

A

0.025%

B

0.06%

C

0.1%

D

0.25%

The cutting speed for drilling aluminium, brass and bronze with carbon steel drills is _________ cutting speed for drilling mild steel with high speed steel drills.

A

Equal to

B

Less than

C

More than

D

None of these

Steel containing ferrite and pearlite is

A

Hard

B

Soft

C

Tough

D

Hard and tough

The correct relationship among displacement thickness d, momentum thickness m and energy thickness e is

A

d > m > e

B

d > e > m

C

e > m > d

D

e > d > m

For flow past a flat plate, if x is the distance along the plate in the direction of flow, the boundary layer thickness is proportional to

A

$$\sqrt {\text{x}} $$

B

$$\frac{1}{{\sqrt {\text{x}} }}$$

C

x

D

$$\frac{1}{{\text{x}}}$$

What is the ratio of displacement thickness to nominal thickness for a linear distribution of velocity in the boundary layer on a flat plate?

A

0.5

B

1

C

1.5

D

2

The ratio of hydrodynamic boundary layer to thermal boundary layer thickness in case of liquid metals is

A

[

A.

B. 1

B

> 1

C

2

During decarburising of a plain carbon steel, the thickness of ferrite layer growth is proportional to

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