A body cools from `50^(@)C` to `40^(@)C` in 5 min. The surroundings temperature is `20^(@)C`. In what further times (in minutes) will it cool to `30^(@)C` ?

Options

A. 5
B. `15//2`
C. `25//3`
D. 10

Answer

C

Explanation

If a body cools from temperature `theta_(1)` to `theta_(2)` in time t, when the surrounding temperature is `theta_(0)`, by Newton,s law of cooling,
`(theta_(1)-theta_(2))/(t)= c[(theta_(1)+theta_(2))/(t)-theta_(0)]`, where c = constant.