### Theory:

Flow of Heat
Flow of heat is the process in which energy (thermal energy) is transferred from one object to another. Generally, the heat is transferred from the hotter object to the colder object. Temperature determines the direction of the heat flow.
1Heat transfer between a cup of coffee and hand.

You are holding a hot cup of coffee.

Would the heat energy transfer from,
1. Your body to the coffee, or
2. The coffee to your body?
The heat will transfer from the cup of coffee to the hand; because, here, the temperature of your body (hand) is lesser than the cup of coffee.

Hot object - Cup of coffee
Cold object - Hand

We know that, the heat is transferred from a hot object to a cold object. So, in this case, Heat is transferred from coffee to your body.

2. Heat transfer between air particles and the human body.

Let us assume, you are standing outside on a summer day. It is $$40$$°$$C$$ outside, Would the Heat energy transfer from,
1. Your body to the air particles, or
2. The air particles to your body?
Fig. - Man standing in a hot sun

We know that the normal human body temperature is $$37$$°$$C$$. In this case,
Hot object - Air particles ($$40$$°$$C$$)
Cold object - Human body ($$37$$°$$C$$

Here, Heat will transfer from air particles to the human body.

3. Heat transfer between air particles and the human body.

Let us assume, you are standing outside on a winter day. The temperature outside is $$23$$°$$C$$. Would the heat energy transfer from,

1. Your body to the air particles, or
2. The air particles to your body?
3.

Fig. - Man standing outside on a winter day

We know that the normal human body temperature is $$37$$°$$C$$. in this case,

Hot object - Human body($$37$$°$$C$$

Cold object -  Air particles  ($$23$$°$$C$$

Here, Heat will transfer from the human body to air particles.