Answer:
a.[tex]1.762\times10^4W[/tex]
b.[tex]8.517\times 10^3W[/tex]
Explanation:
a.Given [tex]T_C=-16.0\textdegree C, \ T_H=20.5\textdegree C, K_b_r_a_s_s=0.8W/m.K\\[/tex]
#To calculate the rate at which heat is being lost by conduction, we first calculate thermal resistance:
[tex]R=K/L\\\\=\frac{5.8\times10^-^3}{0.8W/m.K}\\=7.25\times 10^-^3m^2.K/W[/tex]
#The rate of heat loss can be determined from the equation:
[tex]H=\frac{A}{R}[T_H-T_C]\\\\=\frac{1.4m\times 2.5m\times(20.5--16.0)K}{7.25\times10^-^3m^2.K/W}[/tex]
=[tex]1.762\times10^4W[/tex]
Hence, the rate of heat loss through the window by conduction is [tex]1.762\times10^4W[/tex]
b.Given that thermal conductivity is 0.0500W/m.K and [tex]L_p_a_p_e_r=0.075cm[/tex]
#After covering the window with the paper, there will be additional thermal resistance:
[tex]R_t=R_g_l_a_s_s+R_p_a_p_e_r\\\\R_p_a_p_e_r=\frac{7.5\times 10^-^4M}{0.05W/m.K}\\\\=0.015m^2.K/W[/tex]
#To calculate the rate of heat loss if window is covered,[tex]R_t[/tex]
[tex]H=\frac{A}{R}[T_H-T_C]\\\\=\frac{1.4m\times2.5m\times[20.5--16.0]}{0.015m^2.K/W}\\\\=8.517\times 10^3W[/tex]
#The rate of heat loss when the window is covered is [tex]8.517\times 10^3W[/tex]
