Mass is the amount of matter an object contains. The more matter something has, the more it will weigh. For example, an elephant has more matter than a mouse, so its mass is heavier.
The size of something does not determine how much matter an object has. For example, a golf ball and a ping-pong ball are the same size. However, a golf ball is solid, while a ping-pong ball is hollow because the golf ball has more matter inside, resulting in an excellent mass.
How to Calculate Mass
Typically, mass is measured in kilograms by using a variety of different methods. Here is a brief rundown of how to calculate mass using some of the most popular methods:
- Inertial mass
When calculating inertial mass, you measure how much a given object resists acceleration when applied force. You do this by using a force on your chosen object and measuring the acceleration resulting from that. A general rule to go by is that an object with a small inertial mass will accelerate more than an object with a large inertial mass when the same force is applied.
- Gravitational mass
Gravitational mass is a method of calculating mass that involves measuring how much gravity an object applies to other things. Gravitational mass can also measure how much gravity an object experiences from another object. To calculate the gravitational field of an object, you can allow it to fall freely and then measure its free-falling acceleration. An object free-falling in a smaller gravitational field will accelerate slower than one falling in a larger gravitational field. It is because the gravitational field will be smaller near objects with less active gravitational mass.
- Passive gravitational mass
Passive gravitational mass measures the strength of an object’s interaction with a gravitational field. On the whole, an object’s passive gravitational mass can be calculated by dividing the weight of the object by its acceleration when free-falling. If two objects are located within the same gravitational field, they will experience the same acceleration. Although, whichever object has the smaller passive gravitational mass will experience a smaller force than the object with the larger passive gravitational mass.
How to Calculate Mass in the Classroom
The above methods of measuring an object’s mass are excellent but not handy for use in the classroom. So have a go at these methods of calculating mass, which you can easily do at home or school.
Calculating Mass Using Density and Volume
Step 1: The first step is to get your measurements together. You can start by finding the density of the object. Density measures how closely packed together the matter within an object is. You can quickly look up the density of the material you are working with.
In terms of the units of measurement, the density is typically measured in kilograms per cubic meter, i.e., kg/m³. However, it can be changed to grams per cubic centimeter, i.e., g/cm³ for smaller objects. If you work with liquids, density will be measured in kilograms per liter, e.g., kg/L, or grams per milliliter, i.e., g/mL for smaller objects.
Step 2: Next up, collect your other measurement: volume. Volume is essentially just the amount of space that an object takes up. In terms of units, volume is measured in cubic meters, i.e., m³ for larger solids, and in cubic centimeters, i.e., cm³ for smaller objects. For liquids, the volume of larger liquids is measured in either liters or milliliters, depending on their size. Several formulas for finding an object’s volume vary depending on the object’s shape.
Step 3: Now that you have both the density and the volume of your object, you can start calculating the mass of your object. The formula for how to calculate the mass is:
Mass = Density x Volume
It is essential to keep your units of measurement the same throughout your calculations.
Is Mass the Same as Size?
The simple answer is no. Mass is not the same as size. Mass is determined by the type of atoms within an object and their density. Therefore, mass is entirely independent of size. It means that two objects of the same size can have widely different masses.
What is the Difference Between Mass and Weight?
People tend to confuse mass and weight. Mass and weight are different, as weight is a force created by gravitational attraction to the Earth’s center.
Weight is the force acting on an object weight can change depending on the gravitational force; for example, you would weigh less on the moon as the gravity is weaker there. However, your mass remains the same.
How Many Grams are in a Kilogram?
As you and your class know, mass and weight are two different things. Therefore, when it comes to measuring mass, we need a unit to do so.
The units we use to measure mass are grams and kilograms. Later on, you’ll see just how extensive this list of mass-weighing units is, but the ones your class will use most often are these two. This is because you will be able
So how many grams are in a kilogram? Kilo is a decimal unit representing one thousand, so a kilogram is one thousand grams. Let’s look at an example to see how to work out how many grams are in a kilogram:
How many grams are in 6.2 kg?
Figuring out this answer is far simpler than it may appear. All we have to do is multiply our kilograms by 1000 to get the number of grams. By doing that:
6.2 kg x 1000 = 6200
And there we have it! Working out how many kilograms in several grams is just as easy. We flip this formula around, which would look something like this:
How many kilograms are in 6200 g?
6200 / 1000 = 6.2 kg
How is Mass Measured in Units?
Using the unit of grams, we can get the rest of the metric units using the standard metric prefixes.
| Milligram(mg) | 0.001 gram or 1/1000 gram |
| Centigram(cg) | 0.01 or 1/100 gram |
| Decigram (dg) | 0.1 gram or 1/10 gram |
| Gram(g) | 1,000 |
| Dekagram (dag) | 10 grams |
| Hectogram (hg) | 100 grams |
| Kilogram (kg) | 1,000 grams |
| Metric ton(t) | 1,000 kilograms |
Kids must understand the different units of measurement to be able to convert between them.
Fun Facts about Mass and Weight
- The word ‘mass’ derives from the Greek word ‘maza,’ which translates to ‘lump of dough.’
- Scientists believe the universe’s total mass is between 1052 kg and 1053 kg.
- The gravity of the Earth is not constant but is subject to change. The Earth’s gravity can vary as much as 0.5% depending on your whereabouts on the Earth you are.
- People would weigh different amounts on different planets. For instance, if you weighed 70 kg here on Earth, you would weigh just 26.48 kg on Mars!
