Question

How do the molecules jiggle when an object is heated?

Answer 1

In hotter objects, there is more atomic and molecular motion. Atoms and molecules "jiggle" faster and more wildly. When a hot object touches a colder object, its surface atoms and molecules bang into those of the cold object, causing them to jiggle faster — they heat up. This will continue until both objects are the same temperature, or are in thermal equilibrium, one having lost some heat and one having gained an equal amount. At thermal equilibrium, the heat flow rate is the same in each direction.