The painful stimulus that causes a hand to pull away from hot iron?

The painful stimulus that causes a hand to pull away from hot iron is the heat itself. Heat is a form of energy that can be transferred from one object to another. When heat is transferred from a hot object (like iron) to a cooler object (like your hand), the cooler object gets warmer. This can damage your skin and cause pain. The pain is your body's way of telling you that something is wrong and that you need to move your hand away from the heat source.