What is Mass and Weight? | Definition, Types, Formula & Examples
What is Mass?
Mass is a measure of the amount of matter contained in an object. Mass is a combination of the total number of atoms, atomic density, and type of atoms in an object.
How to Measure Mass?
Mass is usually measured in kilograms, abbreviated as kilograms.
Get Free Counseling
Inertial Mass – Inertial mass is determined by an object’s ability to resist acceleration. For example, if you push two objects under the same conditions with the same force, the object with less mass will accelerate faster.
Gravitational Mass – Gravitational mass is a measure of the force of gravity that one object exerts on other objects. It can also be a measure of an object’s gravitational pull relative to another.
When scientists want to express mass in terms of atoms and molecules, they use the atomic mass unit abbreviated “u”. One atomic mass unit is 1/12 the mass of carbon-12.
What is the difference between Mass and Weight?
Weight is different from mass. Weight is a measure of the force of gravity on an object. The mass of an object will never change, but the weight of an object can change depending on its position. For example, you might weigh 100 pounds on Earth, but in space you would have no weight. However, you will always have the same mass on Earth as in space.
Measuring Weight
In the United States, we usually measure weight in pounds, but in physics when we describe weight as a force, it is usually measured in Newtons, abbreviated as “N”.
Converting Mass to Weight
Since gravity is relatively stable on Earth, the weight will also remain constant. This allows us to use a formula to convert weight to mass or mass to weight. The formula is:
force = mass * acceleration
or
f = ma
In this equation, force equals weight. 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 an object of mass 50 kg?
weight = 50 kg * 9.8 m/s2
weight = 490 N
Is mass the same as size?
No, mass is different from size or volume. Indeed, the type of atom or molecule as well as their density helps determine mass. For example, a helium-filled balloon would have much less mass than a similarly sized object made of solid gold.
The Law of Conservation of Mass
The law of conservation of mass states that the mass of a closed system must remain constant with time. This means that even though the objects in a system change, the overall mass of the system must remain the same.
Interesting Facts about Mass and Weight
The word “mass” comes from the Greek word “maza” which means “piece of dough”.
Scientists estimate the total mass of the universe to be between 1052 kg and 1053 kg.
1000 kg is equal to one ton.
The Greek philosopher Plato said that weight is the natural tendency of objects to seek out their parents.
Earth’s gravity can vary by up to 0.5% depending on where you are on Earth.