A) 2.5s
B) 5s
C) 20s
D) 10s
Correct Answer: D
Solution :
From Newtons law of cooling \[E=\left( \frac{{{\theta }_{1}}+{{\theta }_{2}}}{2}-\theta \right)t\] \[\left( \frac{50+49.9}{2}-30 \right)5=\left( \frac{40+39.9}{2}-30 \right)t\] \[t=\frac{19.95\times 5}{9.95}\] \[=\frac{99.75}{9.95}\approx 10\,s\]You need to login to perform this action.
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