Question

On a hot summer day a concrete driveway may reach a temperature of 50° C. Suppose that a stream of water is directed on the driveway so that the surface temperature is suddenly lowered to 10°C. How long will it take to cool the concrete to 25°C at a depth of 5 cm from the surface? sent full sum ​

Answer 1

Answer:

1.    7086 s.

2.    788 s, 767 s.

3.    72∘C, 533 kJ.

5.    5853 s, 92∘C, 76∘C.

6.    24.1∘C, 39.2∘C.

7.    5400 s, 130∘C.

Explanation: