The units of energy are defined by diffrent units but the important relation is this:

1 J = 1 Ws = 1 Nm = 1 kg m s-2

Where:

• J is energy and stands for Joule.
• Ws is NOT Watt per second(s)! it is Work per second(s).
• Nm is Newton per meter.
• kg m s is Kilogram-meter per second(s) equivalent of a newton-second(s).