5.15 Carbon steel (AISI 1010) shafts of 0.1-m diameter are heat treated in a gas-fired furnace whose gases are at 1200 K and provide a convection coefficient of 100 W/m2 -K. If the shafts enter the furnace at 300 K, how long must they remain in the furnace to achieve a centerline temperature of 800 K?

The time required to reach the center line temperature of 800 K is t = 58 sec

Explanation:

Given data

D = 0.1 m

h = 100

Specific heat for carbon steel (C) = 502.4

Furnace temperature = 1200 K

Final temperature T = 800 K

Initial  temperature = 300 K

From lumped heat analysis

 ------- (1)

Now from equation (1)

㏑ 0.44 =  -(0.001415 ) t

-(0.001415 ) t = - 0.82

t = 58 sec

Thus the time required to reach the center line temperature of 800 K is

t = 58 sec

the positions which points up in upward carbon and down in downward carbon are axial

and vice versa holds true for equatorial positions

so the correct answer with labelled diagram will be

answer:

the answer is 6 valence electrons.

explanation:

valence is the # of electrons on the outer most shell of an atom.

oxygen has 6.

although, the valency of oxygen is 2, because it only needs to make 2 covalent bonds, or gain 2 electrons, to achieve the stable octet configuration of a noble gas.

that's it!

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~ trueboss72