HOSTING A TOTAL OF 318 FORMULAS WITH CALCULATORS

## Change In Energy

Perhaps the most interesting property of thermal energy is that it spontaneously ﬂows from one object to another, provided that the ﬁrst object is hotter than the second.That’s why ice melts in a warm room, ﬁngers freeze on cold metal, and sunlight continuously warms the cool earth.

When energy spontaneously ﬂows from a hotter object to a cooler object, we refer to that energy (while in transit) as heat. Heat is to be contrasted with work, which is any other type of energy transfer .