A body is cooled in 2 min n a room at temperature of `30^@C` from `75^@C` to `65^@C`. If the same body Is cooled from `55^@C` to `45^@C` in the same room, find the time taken (in minute).

Answer

4

Explanation

From `(theta_(1)-theta_(2))/(t)=alpha((theta_(1)+theta_(2))/(2)-theta_(0))`, in first case we have,
`(75-65)/(2)=alpha[(75+65)/(2)-30]`... (i)
For second case , `(55-45)/(2)=alpha[(55+45)/(2)-30]`.... (ii)
Dividing (i) by (2) , `(t)/(2)`=2`
t=4 min