Keep in mind that how "hot" something feels depends on the temperature of the skin in contact with the surface. That, in turn, depends on the heat transfer rate to the skin and the duration of transfer, the combination of which determines the amount of energy transferred to the skin.
For a given type of skin, the rate of heat transfer will depend on the temperature and thermal conductivity of the material of the object, all other things being equal. The amount of energy available to transfer to the skin by means of heat depends on the heat capacity of the object, which is the product of its specific heat and mass.
1.If we hold the two objects in our hands, which object feels hotter?
It depends on how massive the objects are.
While both objects have the same temperature, thermal conductivity and specific heat, object A will have more energy available to transfer due to its greater mass, and thus heat capacity, than B. But if both objects are massive enough so that both of their heat capacities are much higher than that of the skin, they will feel equally "hot". As the heat capacities approach that of the skin, object A will begin to "feel hotter" than B.
EXAMPLE:
Consider two objects made of aluminum having the same temperature prior to being touched. One is an aluminum oven rack the other a piece of aluminum foil, both removed from a hot oven. The aluminum rack will feel much hotter, hot enough to burn the skin, than the aluminum foil, which may barely feel warm. They have the same temperature, thermal conductivity and specific heat. But the heat capacity of the section of foil, and thus the energy available from the foil, touching the skin is negligible compared to the rack.
2.It is evident that object A has more internal energy than B. Does that mean object A feels hotter than B?
Not necessarily, as already pointed out in the answer to (1).
- What actually makes us to feel one object to be hotter or colder than another object? Is it the rate at which heat gets transferred (
which depends on the temeperature difference between the two objects)
or the difference in the internal energy of the two objects?
Both.
As already stated, it is a combination of the rate of heat transfer and the amount of energy available to transfer. The latter depends on the heat capacity of the object, which is related to its internal energy. This is illustrated by the aluminum foil and oven rack example above.
Hope this helps.
