Question

The temperature of a body 'A' is $60°C$ and the temperature of a body 'B' is $122°F$. What will happen when they are in contact with each other?

• A. The heat flows from A to B
• B. The heat flows from B to A
• C. They are in thermal equilibrium
• D. Heat flows from A to B or B to A depending upon the surrounding temperature.

Answer 1

The correct option is A

The heat flows from A to B

The explanation for the Correct Option:

Option A

Step 1: Converting the temperature of body ‘B’ to Celsius-

We know that,

$$\begin{gathered} °F=\left(\frac{9}{5}\right)\times °C+32 \\ \left(°F-32\right)\times \left(\frac{5}{9}\right)=°C \end{gathered}$$

We are given with $122°F$ therefore,

$$\begin{gathered} °C=\left(°F-32\right)\times \left(\frac{5}{9}\right) \\ °C=\left(122-32\right)\times \left(\frac{5}{9}\right) \\ °C=\left(90\right)\times \left(\frac{5}{9}\right) \\ °C=50 \end{gathered}$$

Step 2: Compare and draw conclusions on heat flow:

we have,

The temperature of body ‘A’ is $60°C$

The temperature of body ‘B’ is $50°C$

Hence, the temperature of body ‘A’ is greater than body ‘B’

As per the concept, heat will flow from an object having a higher temperature to an object having a lower temperature. And, Object A has a higher temperature as compared to Object B. Therefore, option (a) the heat flows from A to B is correct.

The explanation for Incorrect Options:

Option (b)

B is at a lower temperature hence heat will not flow from B to A.

Option (c)

Both the temperatures are different, hence, they are not in thermal equilibrium.

Option (d)

As both the objects are in contact, the surrounding can not change the direction of the flow of heat.

Hence, option A is correct.