contains chemical potential energy that can be converted into the kinetic energy of a moving car.  Standard unit of energy: Joules ♦ 1 calorie = 4,184 joules  Thermal Energy – The kinetic energy of many particles  Most important type of energy • Represents the total kinetic energy of the many individual particles (atoms and molecules) moving randomly within a substance like a rock or the air or the gas within a distant star. ♦ All objects contain thermal energy even when they are sitting still, because the particles within them are always jiggling about randomly • Thermal energy measures the total kinetic energy of all the randomly moving particles in a substance white temperature measures the average kinetic energy of the particles. • Thermal energy depends on temperature, because a higher average kinetic energy for the particles in a substance must also lead to a higher total energy • Thermal energy depends on the number or density of particles ♦ Oven vs. boiling water  Potential Energy in Astronomy  Two types: gravitational potential energy and the potential energy of mass itself (mass-energy)  An object’s gravitational potential energy depends on its mass and how far it can fall as a result of gravity. • An object has more gravitational potential energy when it is higher and less when it is lower. ♦ Ex: if you throw a ball up into the air, it has more potential energy when it is high up than it does near the ground