Consider a rectangular graphite slab as shown in

the figure of width $1m,$ thickness of $4cm$ and

length of $10cm.$ The slab was heated in an oven to

$950C$ and taken out, kept in a room for $10$

minutes. The convective heat transfer coefficient of

the air in the room is $100\frac{W}{m^2}K$ and the room

temperature is $T_{}=25C.$

a$)$ Can this graphite slab cooling be treated as

lumped$-$capacity cooling? $(2$ point$)$

b$)$ What is the final temperature of the slab

after $10$ minutes? $(3$ points$)$

Properties: $=2210k\frac{g}{m^3}$;$C_p=709\frac{J}{k}g*K$;$k=1950\frac{W}{m}*K$;$T_{mp}=2273K=2000C$