Q吸=cm(t-t0)=4.2×10ˆ3J/(kg.℃)*40kg*30°C=5.04×10ˆ6J
Q接受=Q吸÷50%=1.008×10ˆ7J
1.008×10ˆ7J÷[1.26×10*3J/(m²·s)*1.6m²]=5000s