CBSE BOARD XII, asked by singhmasuta2237, 8 months ago

Steel balls 12 mm in diameter are annealed by heating to1150 K and then slowly cooling to 400 K in an air environment for which T[infinity] = 325 K and h = 20 W/m2 K. Assuming the properties of the steel to be k = 40 W/m K, rho = 7800 kg/m3
, and c = 600 J/kg K, estimate the time required for the cooling process.
Now the air temperature increases with time as T[infinity] (t) = 325 K + at, where a = 0.1875 K/s. Find an expression for the ball temperature as a function of time T(t).

Answers

Answered by parsishilpa22
1

Explanation:

Steel balls 12 mm in diameter are annealed by heating to 1150 K and then slowly cooling to 400 K in an air environment for which T∞=325KT

=325K and h=20W/m2⋅Kh=20W/m

2

⋅K. Assuming the properties of the steel to be k=40W/m⋅Kk=40W/m⋅K, ρ=7800kg/m3ρ=7800kg/m

3

, and c=600J/kg⋅Kc=600J/kg⋅K, estimate the time required for the cooling process.

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