Difference Between Mass and Weight
Why do scientists measure celestial bodies with mass and not weight to describe the properties of the star’s characteristics such as luminosity, temperature, and age? What is even mass? What is weight?
Why do scientists measure celestial bodies with mass to describe the properties of the star using characteristics such as luminosity, temperature, and age? What is even mass? Mass is a factor that determines almost everything of a star. People use the words mass and weight incorrectly though. In Lamen’s terms, mass is how much stuff there is on the object. For example, a filled-up 2-liter water bottle has more mass than an empty 2-liter water bottle because it has more stuff than the other. You can also think of this concept using the analogy of a bank. Let’s say you have two bank accounts. Bank account A has around $500,000 and bank account B has about $20,000. When someone asks you, “Which one has the most amount of money?” you would say bank account A. In this analogy, the amount of money is the stuff that an object has and the bank account is the object. Mass is measured in kilograms. The simplest way to calculate mass is by using Newton’s second law of motion which is: 𝛴 F = ma.
𝛴 F is the net force. This is when you take into account all the forces acting on an object and find its overall force. For example, let’s say there is a book on the table and you and your friend push on the book on opposite sides. You push the book with about 12 newtons to the right and your friend pushes in the opposite direction with a force of 8 newtons. To find the net force, we have to subtract 8 N from 12N and we’ll find out that the net force is 4N to the right.
Weight, on the other hand, is a different thing. Weight is how much gravitational force an object experiences from another thing. On planet Earth, the weight of an object is how much of the Earth’s gravitational force an object would feel(technically it’s not a force, but details on that for another time…). We can calculate weight by using the following formula: w = mgh, where w is the weight(newtons), m is mass(kilograms), and h is the height(meters). The one main thing about weight is that it can change based on the local strength of the gravitational force. For instance, you might weigh 60 newtons(newtons is the unit for weight) on the moon where its gravitational strength is only ⅙ of the Earth, you’ll weigh 6 newtons.
Now with some background info, we can understand why scientists use mass instead of weight as a celestial body’s characteristics. Mass is an intrinsic property meaning that the value will always stay the same wherever you are but weight will change making it difficult to do calculations when the values can vary.
