The energy of a body is defined as its capacity for doing work.

(1) It is a scalar quantity.

(2) **Dimension :** [ML^{2}T^{2}] 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 = 10^{7} erg

1 eV = 1.6 × 10^{–19} Joule

1 KWh = 3.6 × 10^{6} Joule

1 Calorie = 4.18 Joule