mass

Every object is made up of matter. Mass is defined as the amount of matter in an object. It is a combination of the total number of atoms, the density of the atoms and the type of atoms in an object. The more matter an object has, the bigger it is, and the more mass it has. Mass is measured in kilograms, kg or grams, g. Things that have a big mass are harder to move, or harder to stop than objects with little mass.

Mass is how heavy something is without gravity. This means the mass of an object is the same on earth and in space (or another planet). For example, a ball of mass 100 gm will have same mass everywhere, even on the moon.

The word “mass” comes from the Greek word “maza” meaning “lump of dough”.

Scientists estimate the total mass of the universe is between 10⁵²kg and 10⁵³kg.

Mass is usually measured in kilograms (kg) or grams (g).

1000 kg is equal to a metric ton.

There are different ways of determining the quantity of mass. Two of the most commonly used are:

• Inertial mass – Inertial mass is determined by how much the object resists acceleration. For example, if you push two objects under the same conditions with the same amount of force, the object with the lower mass will accelerate faster.
• Gravitational mass – Gravitational mass is a measurement of how much gravity an object exerts on another object. It can also be the measurement of how much gravity an object experiences from another object.

 

Mass is NOT the same as weight. The difference is that weight is determined by how much something is pulled by gravity. Weight is the measure of the force of gravity on an object. The mass of an object will never change, but the weight of an item can change based on its location. For example, you may weigh 100 pounds on Earth but in outer space, you would be weightless.

Mass is a scalar quantity; weight is a vector quantity.

• The quantities which describe only the numerical value of a given force are known as scalar quantities. For example, mass, speed, time, temperature, etc.
• The quantities which describe the direction along with the numerical value of a given force are known as vector quantities. For example, weight, velocity, acceleration, etc.

Since gravity is fairly consistent on Earth, the weight will be consistent as well. This allows us to use a formula to convert weight into mass or mass into weight. The formula is:

Force = mass * acceleration

F = m*a

In this equation force is equal to the weight. The acceleration is the acceleration caused by gravity "g" which is 9.8 m/s². Now we can substitute weight for mass and 9.8 m/s2 for acceleration to get the formula: 

Weight = mass * g
Weight = mass * 9.8 m/s2

Example: What is the weight of a 50 kg mass object? 

Weight = 50 kg * 9.8 m/s2
Weight = 490 N 
 

Always remember 1 Newton = 101.97162129779 grams

Therefore, 5 Newton weight on Earth is equal to approximately 500 grams or 0.5kg mass.

Mass is different than size or volume. This is because the type of atoms or molecules, as well as their density, helps to determine the mass. For example, a balloon filled with helium will have much less mass than a similar sized item made of solid gold. 

When scientists want to convey an object's mass in relation to atoms and molecules, they use the term ‘atomic mass unit’ (u). This means one atomic mass unit is equal to 1/12 of the mass of carbon-12.

The amount of mass that is within a certain space is called ‘density’ and is measured in grams per cubic centimeter or g/cm3. The symbol most often used for density is ρ (the lower case Greek letter rho), although the Latin letter D can also be used.

The density of a substance is equal to mass divided by volume or D = m/v.

The Law of Conservation of Mass states that the mass of a closed system must remain constant over time. This means that although changes are being made to the objects in a system, the overall mass of the system must remain the same. The state of the object can change. For instance, an ice cube will have the same mass as the water that forms as the ice cube melts.