3.1 Energy

Energy is the product of force and distance. It is, essentially, how much force applied over how much distance. As a result, in symbols, $E=FD$ . The unit of energy is $\rm Nm = kg\cdot ms^{-2}\cdot m$ . Now, that a bit long. That's why Joules is a shorthand of the unit of energy: $\rm J = Nm$ .