# Mass Formula

The Mass concept decides the amount of matter is present in an object. It is a quantitative measure of an object’s resistance to acceleration. Not to get confused with the term weight, Weight is not a mass but the amount of gravitational force that acts on the given body.The molar mass, M is the physical property which is defined as the mass of a chemical substance divided by its amount of the substance. The SI unit of molar mass is kg/mol.

The mass formula is given as

Where,

ρ = density and

**v** = the volume

The weight mass formula is given as

m = w / g

Where,

**w **= weight,

**m **= mass,

**g **= gravity

The mass formula is also given as

** m = F / a**

If acceleration itself is the gravity, then

**M = F / g**

Where,

**F **= force

**G =** gravity

The well known Einstein’s mass-energy relation that provides mass energy formula as

** m = E / c****2**

Where,

**E **= energy,

**m **= mass,

**c **= speed of light

The kinetic energy mass formula is given as

**K.E = ½ mv****2**

Where,

**m **= mass,

**v **= velocity.

**Example 1**

Calculate the mass if the weight of a body is 90 N.

**Solution:**

Given,

weight of the body = 90 N,

The mass of the body is expressed by

m = w / g

= 90 / 9.8

= 9.183 kg

**Example 2**

Determine the mass of a body if the K.E is 60 J and velocity is 7m/s.

**Solution:**

Given:

Kinetic energy, k.E = 60 J,

Velocity, v = 7 m/s

the mass is expressed by

m = 2 k.E / v2

= 2 ×60 / 72

= 2.44 kg