1. When we write a unit in full, the first letter should not be in capital.
Example: metre and not as Metre kilogram and not as Kilogram

2. Name of scientist as the symbols of unit should be in upper case (capital) letter
Example: N for newton, J for joule.

3. The singular form of the unit should be used.
Example: km and not as kms, Kg and not as kgs

4. At the end of the abbreviations there should be no full stop.
Example: mm and not as mm, kg and not as kg.

5. The degree sign is omittedwhen temperature is expressed in Kelvin.
Example: 273K not as 2730 K

6. Accepted symbols should only be used.
Example: ampere is represented as ‘A’ and not ‘amp’
second is represented as ‘s’ and not ‘sec’

7. Not more than one solidus or slash should be employed. But effort should be made to avoid use of solidus or slash.
Example: J/k.mol or Jk.mol^-1 but not J/k/mol
J kg^-1K^-1 but not J/kg/K

8. Between the number and the symbol of the unit, one letter space is always to be left.
Example: 2.3 m and not as 2.3m
Kg m s^-1 and not kg ms^-1

9. A physical quantity in numerical value should be expressed as p= a × 10m
Here ‘a’ is a number between 1 and 10 and ‘m’ is the appropriate power of 10.
Example: velocity of light c = 2.997 × 10 ms^-1 .

Latent Heat is defined as the heat absorbed or released per unit mass of the substance when the substance changes its phase at the constant temperature.

Latent heat of fusion is defined as the quantity of heat in calories required to transform 1 gm of solid substance at its melting point into liquid of the same temperature.

Mathematically,
Latent heat of fusion (L) = Heat (Q) / mass (m)

Dimensional formula of Heat(Q) = M¹L²T^-2
Dimensional formula of mass = M¹L⁰T⁰

Putting these values in above equation we get,
Dimensional Formula of Latent Heat = M⁰L²T^-2
SI unit of Latent Heat is Joule kg^-1

Note:- Dimensional formula of latent heat of fusion is same as Latent heat. Similarly SI unit of Latent heat of fusion is same as Latent Heat.

Power (P) is the rate at which work is done. It is the amount of energy consumed per unit time.

Formula of power is work / time

Unit of power is Joule second-1 or watt

Symbol is w

Work or Energy

When a displacement of an object occurs due to force it is said the work was done upon the object. In order for a force to qualify as having done work on an object, there must be a displacement and the force must cause the displacement. Energy is defined as the capacity to do work.

Formula for Work or Energy is Energy = force × displacement

E = f × d

Unit for Work or Energy is Joule

Symbol for Work or Energy is J

Impulse (Imp or J)

When an object is acted upon by a force for an interval of time, the change of momentum of that object is Impulse. Simply, Impulse is the product of force and time for which it acts.  Impulse is also a vector quantity in the same direction as force. Impulse helps you calculate the change in momentum, or you can use impulse to calculate the average impact force of a collision.

Formula for Impulse = force × time

J = f × t

Unit of Impulse is Newton second

Symbol of Impulse is Ns