A physicist must make sure that the temperature of a metal at 0 deg C gets no colder than -80 deg C. The physicist changes the metal's temperature at a steady rate of -4 deg C per hour. For how long can the physicist change the temperature?

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Answer 1 · 2017-02-11T09:35:54

20 hours

First let us take the metal as # x #

If the rate of decreasing temperature is -4C/1hr and the physician cannot decrease the temperature beyond -80C.

The time in which he can the physicist change the temperature or the time taken by metal to reach -80C

= #"-80C"/ "4C/ 1hr"#

= #-80 / -4#

= 20 hours

so the time in which he can the physicist change the temperature or the time taken by metal to reach -80C is 20 hours