Mass – Definition with Examples

Table of Contents

    Hello Brighterly learners! Today, we’re embarking on an adventure deep into the world of physics, where we’ll be exploring a concept that impacts our everyday lives in countless ways, whether we’re aware of it or not. Yes, we’re talking about the concept of mass. It’s so common that we often take it for granted.

    What is mass exactly? How does it differ from weight? And how do these scientific concepts impact the world around us? These are just some of the questions we’ll be answering today. As always at Brighterly, we aim to make complex concepts easy to grasp.

    What Is Mass?

    When you hear the term mass, what comes to mind? You may think of a crowd of people or perhaps something related to religion. In the world of physics, however, mass has a completely different meaning. Mass is a fundamental property of an object. It is the amount of matter contained in an object.

    You can think of mass as the number of building blocks (like tiny Lego pieces) that make up an object. The more blocks, the greater the mass. But these are not ordinary Lego pieces, they’re atoms and molecules – the smallest units of matter. So, if we could count the number of atoms in an object, we would know its mass! Isn’t that fascinating? Don’t worry, we won’t ask you to count atoms, but we will delve further into this intriguing concept.

    Definition of Mass

    So, how do scientists define mass? According to Physics, mass is the amount of matter in an object. You might also hear it referred to as ‘inertia’ because mass is what resists change in motion. Imagine trying to push a large boulder versus a small pebble. The boulder, with more mass, is much harder to move, isn’t it? This shows mass at work!

    Definition of Weight (as a Comparable Concept)

    Now let’s talk about a related concept, weight. Weight is the force exerted by gravity on an object’s mass. It is calculated by multiplying an object’s mass by the acceleration due to gravity.

    Sounds complicated? It really isn’t. Imagine you’re holding an apple. The apple’s weight is the force you feel pulling it down towards the ground, thanks to Earth’s gravity. You may notice, if you’ve ever jumped in a pool, that things seem lighter in water. That’s because the water counteracts some of gravity’s pull. So, weight can change depending on where you are (like on the moon), while mass stays the same.

    Properties of Mass

    Now let’s dig deeper into the properties of mass. The most important thing to remember is that mass is constant. It doesn’t change, no matter where you are in the universe. So, whether you’re on Earth, the Moon, or floating in outer space, your mass remains the same.

    Another property of mass is that it can neither be created nor destroyed, according to the law of conservation of mass. This means that the total mass in a closed system remains constant, regardless of the physical and chemical changes that might occur within that system. For example, if you melt an ice cube, the mass of the water produced is equal to the mass of the ice cube you started with.

    Properties of Weight

    On the flip side, the weight of an object can vary depending on the gravitational force acting on it. For example, you would weigh less on the Moon than on Earth, due to the Moon’s weaker gravitational pull. So, weight is not constant.

    Another property of weight is that it always acts downwards towards the center of the planet. This is why we always fall downwards and why we need to exert an upward force to lift something.

    Difference Between Mass and Weight

    So far, we’ve learned that both mass and weight are related to the amount of matter in an object. However, the key difference lies in their constancy: mass is always constant, while weight varies depending on the gravitational force.

    This is why astronauts in space are weightless, even though their mass is unchanged. Without the gravitational pull of the Earth acting on their mass, they have no weight!

    Units of Mass and Weight

    In the metric system, the unit of mass is the kilogram (kg), and the unit of weight is the Newton (N). In the Imperial system, often used in the U.S., mass is measured in pounds (lb), and weight can also be expressed in pounds (lb). This is a bit confusing, but remember, the pound is a unit of force in the Imperial system, while it’s a unit of mass in the metric system.

    Converting Units of Mass

    Converting units of mass is quite straightforward. In the metric system, you simply move the decimal point. For instance, 1 kilogram is equal to 1,000 grams. In the Imperial system, things are a little more complex. For example, 1 pound is equal to 16 ounces.

    Converting Units of Weight

    Converting units of weight follows a similar process. In the metric system, 1 Newton is approximately equal to 100 grams. In the Imperial system, weight is often given in pounds, but can also be expressed in ounces, tons, and other units.

    Practice Problems on Mass and Weight

    Let’s put your new knowledge to the test with some practice problems on mass and weight:

    1. If a book has a mass of 1 kg, what is its weight on Earth?
    2. If an astronaut weighs 176 pounds on Earth, what would be his weight on the Moon, where the gravitational pull is one-sixth that of Earth?


    What an enlightening journey we’ve had today! Together, we’ve unravelled the fascinating concepts of mass and weight, diving into their definitions, exploring their unique properties, and understanding their differences. We even delved into the units of measurement for these scientific quantities and discussed how to convert between different units.

    Remember, even though the concepts of mass and weight are fundamental to physics, they also play an important role in our everyday lives. So the next time you lift a heavy box, take a leap into a swimming pool, or marvel at the sight of astronauts floating in space, you’ll have a deeper understanding of the science behind these phenomena.

    As always, keep that curious spirit alive, and keep exploring the world around you. Keep asking questions and seeking answers, and remember that learning is a lifelong journey. And of course, remember to come back to Brighterly whenever you’re hungry for more knowledge!

    Frequently Asked Questions on Mass and Weight

    Does my weight change in space?

    Yes, it does! In space, the gravitational pull that gives weight to your mass is almost non-existent. That’s why astronauts float around in space stations. Even though their mass remains the same as on Earth, the force of gravity acting on that mass is so minimal that they experience weightlessness.

    If I lose weight, do I lose mass?

    Absolutely! When you lose weight, you are effectively losing mass. This might happen through the burning of stored fat in your body, or by losing muscle mass. Both fat and muscle contribute to your overall body mass, so when they decrease, your mass decreases, and so does your weight.

    What unit is used for weight in the metric system?

    In the metric system, weight is measured in Newtons (N). A Newton is the amount of force required to accelerate a one-kilogram object by one meter per second squared. So when we say an object’s weight is, for example, 10 N, we mean that the gravitational force acting on it is enough to accelerate it at a rate of 10 meters per second squared.

    Information Sources:
    1. USGS: Earth’s gravity
    2. Wikipedia: Mass
    3. Wikipedia: Weight

    Kid’s grade

    • Grade 1
    • Grade 2
    • Grade 3
    • Grade 4
    • Grade 5
    • Grade 6
    • Grade 7
    • Grade 8
    • Grade 9
    • Grade 10
    • Grade 11
    • Grade 12
    Image full form