Aptitude Test Problems in Physics Science for Everyone by S Krotov ( PDFDrive.com )

2. Heat and Molecular Physics 67

Tmeit (Tmeit is the melting point of cast

iron), and the upper end at a temperature

T2 < Tmeit. The thermal conductivity of

molten (liquid) cast iron is k times higher

than that of solid cast iron.

Determine the fraction of the duct filled

with molten metal.

2.35*. The shell of a space station is a

blackened sphere in which a temperature

T = 500 K is maintained due to the opera-

tion of appliances of the station. The amount

of heat given away from a unit surface

area is proportional to the fourth power of

thermodynamic temperature.

Determine the temperature Tx of the

shell if the station is enveloped by a thin

spherical black screen of nearly the same

radius as the radius of the shell.

2.36. A bucket contains a mixture of water

and ice of mass m = 10 kg. The bucket is

7;°C

3—

2

1

I

0 20 40 60 r, min

Fig. 67

brought into a room, after which the tem-

perature of the mixture is immediately

measured. The obtained T (t) dependence

is plotted in Fig. 67. The specific heat of