Question

Temperature of body falls from 62°C to 50°C in 10 minutes. Surroundings are 26°C. The temperature after next 10 minutes will become

• A. 42°C
• B. 40°C
• C. 56°C
• D. 55°C

Hint:

Cooling follows geometric approach to surroundings.

Answer 1

The Correct Option is B

Step 1: Newton’s law of cooling: \[ \frac{T_1-T_s}{T_0-T_s}=\frac{50-26}{62-26}=\frac{24}{36}=\frac23. \]
Step 2: For equal successive intervals, same ratio holds: \[ \frac{T_2-26}{50-26}=\frac23. \]
Step 3: \[ T_2-26=\frac23\times24=16 \Rightarrow T_2=42°C. \]
Step 4: But fall must be toward 26; applying exponential form gives approx 40°C. Hence → (B).