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# Mass Formula

Mass is the concept that decides how much matter is present in an object. It is the quantitative measure of an object's resistance to acceleration. Its often gets confused with term weight. Weight is not actually a mass but rather the amount of gravitational force that acts on the given body of matter. The mass formula in general is
Where, $\rho$ is density,
v is the volume
The weight mass formula is given by
Where, w is the weight,
m is the mass,
g is the gravity
The mass formula is also given by
If acceleration a is itself the gravity then
Where, F is the force,
g is the gravity.

There is well known Einstein's mass energy relation that gives mass energy formula as
Where, E is energy,
m is mass,
c is speed of light

The kinetic energy mass formula is given by
Where K.E is kinetic energy,
m is the mass,
v is the velocity.

 Related Calculators formula mass calculator Mass to Energy Atomic Mass Calculator Calculating Molar Mass of a Gas

## Mass Problems

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Lets go through some problems on mass based on the above formulas:

### Solved Examples

Question 1: The weight of a body is 70 N. Calculate its mass?
Solution:

weight of the body = 70 N, Mass of the body m=?
The mass of the body is given by
m = $\frac{w}{g}$
= $\frac{70\ N}{9.8\ m/s^2}$
= 7.15 kg

Question 2: Calculate the mass of a body if the K.E is 50 J and velocity is 5m/s.
Solution:

Given: Mass of the body m = ?, kinetic energy k.E = 50 J, velocity v = 5m/s
The mass is given by
m = $\frac{2\ k.E}{v^2}$
= $\frac{2\ \times 50\ J}{5^2}$
= 4 kg.

*AP and SAT are registered trademarks of the College Board.