"Too Hot/Too Cold"

One example that heats up at a different rate is  hot water heating up a piece of metal the reason why I think that the metal heats up at a different rate is because metal is made of a very solid molecule. Another example that an object heats up another object at a different rate is cold water, if you had cold water into hot water which you can only add cold water into hot. Also if you turn on a stove and put a ( let's a piece of metal the metal is going to heat up at a different rate because it takes a certain time to hear up the molecule of the object.