$3.$ If the inner temperature of a $250[$mm$]$ thick furnace wall made of bricks with an average thermal conductivity of $0\mathrm{.}2[$kcal$/$mhr$.]$ is $750$ and the outer temperature is $250,$ what is

the heat loss per unit area?

$4.$ The thermal conductivity of a cylindrical wall with an inner diameter of $5[$cm$]$ and an outer diameter of $10[$cm$]$ is $0\mathrm{.}1[$kcal$/$mhr$.$ If the internal temperature is $100[]$ and the external temperature is $20[],$ find the work loss per $1[$m$]$ of the motor

$.$

$5.$ There is a wall $8[$m$^2]$ with a thickness of $20[$cm$].$ The inner temperature is $600[]$ and the outer temperature is $250[].$ When the heat conduction of the wall is $2[$kcal$/$m$.$hr$],$ calculate the heat transfer rate.

$6.$ The battle takes place through the furnace wall. Furnace wall thickness $200[$mm$]$ Average heat conduction $5.$ At $3\mathrm{.}3[$kcal$/$m$.$h r$.],$ what is the heat resistance per $1[$m$^2]$ of Nobaek?

$7.$ The thickness of the furnace wall is $200[$mm$],$ and the outside is insulated with $75[$mm$]$ asbestos. If the inner temperature of the wall is $400[]$ and the outer temperature is $38[],$ find the amount of heat lost for $3[$hr$]$ in $10[$m$^2]$ of the furnace wall. The average thermal conductivity of the furnace wall and asbestos is $3\mathrm{.}3,0\mathrm{.}13[$kcal$/$mhr$.].$

$8.$ There is a paddle with a thickness of $20[$cm$].$ The inner wall of the furnace is $900[]$ and the outer wall is $370[$D$.$ When the area of $$the furnace wall is $10[$m$^2],$ how much heat is lost per unit time $[$kcal$/$hr$]?$

$($However$,$ the thermal conductivity of the furnace wall is $3\mathrm{.}2[$kcal$/$m$.$hr$].)$

$9.$ There is a three$-$story brick wall. Internally, the thermal resistance is $1\mathrm{.}5$kcal$/$hr$.$

$1\mathrm{.}3$kcal$/$hr C$,0\mathrm{.}25$kcal$/$hr$.$ It is $.$ When the internal temperature is $760$ and the external wall temperature is $38,$ what is the temperature between the second and third walls?

$10.$ In Section $1,$ the outside of the tank was insulated with $32[$mm$]$ thick glass wool $($k$=0\mathrm{.}037$kcal$/$mhr$),$ and the inner surface of the glass wool was $35[]$ and the outer surface was $18[].$ What is the heat loss $[$kcal$/$hr$]$ per $100[$cm$^2]$ of surface area?