Difference Between Weight and Mass

Difference Between Weight and Mass

What is the difference between mass and weight? Most of us would just shrug off this question as being pointless. Both of these terms are so frequently said/used in place of one another that it is easy for one to be ignorant of the dissimilarity here. Realistically speaking, if we were to break down the technicality of each and every dissimilarity, we would end up with an endless article.

Well, an endless article may be an overstatement, but you get the idea. To keep this discussion short and engaging a good overview regarding how are mass and weight different should sufficiently clarify any ambiguity. As we don’t want to bore you with mundane details, all the while teaching you something of significance. However, before venturing forth, we would like you to familiarize yourself with the following information: Weight=mass x gravity; gravity-Earth=10m/s2; gravity-moon=1.6m/s2

Definition of Weight

Weight is a derived-quantity. It’s a vector-product of two physical-quantities. This term, “derived-quantity,” forms a foundational difference between weight and mass. To keep our explanations simple to understand, it’s best if an example is presented. A sack of potatoes is found to be of 5 kg.

If one were to estimate the weight/load of the sack, it would be roughly equivalent to 50N here (where “N” denotes “Newtons”). Interestingly enough, if one were to grab a spaceship and zipped all the way over to the moon with the same sack, the new load would be equivalent to roughly 8N.

Why the discrepancy? Well, if you recall, both these places possess varying strengths of field-attraction. This example will help explain the difference between mass and weight better during our discussion of the other term next.

Definition of Mass

Mass is a basic-quantity. It is a part of seven basic physical-quantities. These seven basic-quantities help in forming other physical-quantities. Its SI unit is Kg/kilogram. As stated in our discussion, we are going to continue our previous example presented above to give you the best possible grasp of your question of what’s the difference between mass and weight?

Close inspection reveals that regardless of where the sack is carried off to. The value 5 kg does not change. That’s because the mass of our sack is 5 kg, and this value is eternal. As mass cannot be destroyed/created. Hence, a co-depended relation between the two is established where one is defined as being fixed and the other as non-fixed.

Weight vs Mass Comparison Table

Basis of Comparison Mass   Weight
Mean   Fixed-amount of substance/matter Force resulting from interaction of attractive fields  
SI Unit   Kg N
Type   Scalar/directionless Vector/direction-dependent
Eternal   Yes No
Formula Yes; m=W/g Yes; W=m.g
Sign Always positive and never 0 Maybe positive or negative depending on direction; may also be 0
How is it measuredComparative analysis via materials of known mass; beam-balanceNewton-scale, spring-balance, etc.

Conclusion of the Main Difference Between Weight vs Mass

This brief discussion should provide satisfactory answers to some queries regarding what is the difference between weight and mass. The best way to highlight the distinction between the two is through our previously given formula; Weight=mass x gravity.

This signifies two major points; the directly proportional relation between these two terms and how a physical-quantity may be derived from a basic-quantity. The distinction though interestingly subtle, hardly affects our practical lives. The ignorant is likely to continue using the two without any change.

However, for those with lingering curiosity, further review of literature is recommended, as this is an interesting discussion indeed. Modern Classical physics is a very interesting pick for you to expand your understanding.