for heat to flow there must be a temperature difference?

Question

explain why certain objects feel cold and others feel warm

Answer 1

A temp. difference must be exist for heat to flow.
Rate of heat flow follows the eqn dQ/dt = kA(dT/dx) , which dQ/dt =rate of heat flow
k =thermal conductivity
A =cross-sectional area
dT/dx =temperature gradient

Object feel cold bcox it absorb energy(heat) and oppositely, when object release heat it will be feel warm.
The absorption of energy called endothermic while release of energy called exothermic.

Answer 2

Imagine two different objects outside on a cold day: a nail and a piece of paper. Touch the nail, it feels cold, touch the paper, it feels warmer. But why? As others have mentioned, it does depend on the thermal conductivity of the object, which determines how much heat will flow from your body to the object. So a nail will cause lots of heat to be drawn from your fingers to the nail, while a piece of paper much less heat. This has the effect of making the nail feel colder. But there is something else that is important. That is the heat capacity of the object. This determines how much heat must be added to an object to increase its temperature 1 degree. For a nail, it takes a lot of heat to produce one degree temperature change, while for a piece of paper, because of its low mass, it takes much less. Hence, it is much more difficult to warm a nail from you hands than a piece of paper. Hence, the nail feels colder than the paper. To put it simply, if you touch a nail on a cold day, the nail cools down your finger, but if you touch a piece of paper, your hand warms the paper.

Bozo

Answer 3

It is relatively hot or cold. Depending upon the temperature at which your hands are, when you touch an object, you feel cold or hot based on the temperature difference between your body and object. That is why, for some. it may not be very hot when one person feels so. Same object at different temperatures and in the process of heat transfer from one end to other hence like a bucket of water and in which hot water is poured experienced when you feel immediately after pouring.
VR

Answer 4

Yes, for heat to transfer temperature difference is a must criterion to be fulfilled. It is the tendency of heat to flow from higher temperature to lower temperature. Everything you see around you(except with some energy sources such as a electric bulb, heater, refrigerator etc) are at same temperature.

Now when every thing is at same temperature why do you feel some object hot and other cold??? Lets take an example: On a cold winter day, a rod of iron and a piece of wood are at same temperature. But we feel iron colder than wood. It is because Iron offers less resistance to flow of heat than an wood piece.

As Iron rod offers less resistance it withdraws more amount of heat than an wood piece leaving you feel colder than if you have touched wood. (Remember you are an energy source - Your body burns calories to keep your body at constant temperature which is higher than that of surrounding on a cold winter day.)

Answer 5

The temperature difference is important for sure. Why certain objects feel cold and others warm depends on the heat conductivity mostly. Metals are good conductors of heat, while wood is a poor conductor. Metals “suck” warmth out of your finger, while wood is more “friendly” to you.