What causes you to have the sensation of heat or cold when you touch an object?

Question

At what common temperature will a block of wood and a block of metal both feel neither hot nor cold when you touch them?

If you blow air onto your hand, why will it feel different if you blow with your mouth wide open versus blowing with your lips held closely together? Explain what happens to cause this sensation on your hand.

Answer 1

Wow this one's easy. They're called nerves.

Answer 2

either you absorb energy or you emit energy when you are in contact with an object which is hot or cold respectively. this change in energy level in you from the normal nature before the contact make your nerve system to realise this.