An interesting thing about the final speed of an object descending (with no friction) from some given height h , along a sloping surface: one can change the slope, one can even change the shape of the surface--yet the final speed v with which it reaches the bottom will always be the same. ... Heat . ... Electric . ... Like currencies, different kinds of energy have a certain exchange rate: in the exchange between kinetic or potential energy and heat, for instance, one calorie equals about 4.18 joules. ...