Certain quantity of water cools from 70°C to 60°C in the first 5 minutes and to 54°C in the next 5 minutes. The temperature of the surroundings is

Question

Certain quantity of water cools from 70°C to 60°C in the first 5 minutes and to 54°C in the next 5 minutes. The temperature of the surroundings is (A)  45 ° C  (B)  20 ° C  (C)  42 ° C  (D)  10 ° C

Tardigrade Admin · Accepted Answer

(60-70/5)=- K (65- T ) (54-60/5)- K (57- T ) (-10/-6)=(65- T /57- T ) 285-5 T =195-3 T 90=2 T T =45°

Q. Certain quantity of water cools from 70 $^{\circ}$ C to 60 $^{\circ}$ C in the first 5 minutes and to 54 $^{\circ}$ C in the next 5 minutes. The temperature of the surroundings is

$4 5^{\circ} C$

$2 0^{\circ} C$

$4 2^{\circ} C$

$1 0^{\circ} C$

$\frac{60 - 70}{5} = - K (65 - T)$
$\frac{54 - 60}{5} - K (57 - T)$
$\frac{- 10}{- 6} = \frac{65 - T}{57 - T}$
$285 - 5 T = 195 - 3 T$
$90 = 2 T$
$T = 4 5^{\circ}$

Q. Certain quantity of water cools from 70∘C to 60∘C in the first 5 minutes and to 54∘C in the next 5 minutes. The temperature of the surroundings is

45∘C

20∘C

42∘C

10∘C