The energy of a body is defined as its capacity for doing work.
(1) It is a scalar quantity.
(2) Dimension : [ML2T2] it is same as that of work or torque.
(3) Units : Joule [S.I.], erg [C.G.S.] Practical units : electron volt (eV), Kilowatt hour (KWh), Calories (Cal)
Relation between different units :
1 Joule = 107 erg
1 eV = 1.6 × 10–19 Joule
1 KWh = 3.6 × 106 Joule
1 Calorie = 4.18 Joule
