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### Mass of electrons

Posted: Mon Oct 15, 2018 11:42 am
When calculating the mass of an electron, why is the SI unit in kg and not grams? Wouldn't grams make more sense?

### Re: Mass of electrons

Posted: Mon Oct 15, 2018 12:29 pm
Because other units are based on kg, like joule(J) for energy and watt(W) for power. Joule is ‎kg⋅m2⋅s−2, and watt is ‎kg⋅m2⋅s−3. Using kg saves us from changing unit of mass during calculation.

### Re: Mass of electrons

Posted: Tue Oct 16, 2018 9:46 pm
The SI unit for mass is always kg, which can be confusing for measuring objects with very small mass (like electrons). Just know that in equations, like 1/2mv^2 for kinetic energy, the mass must always be represented in kg.

### Re: Mass of electrons

Posted: Tue Oct 16, 2018 10:28 pm
It's more practical to use kilograms to measure things. Though we measure the weight of small things like electrons in chemistry, kilograms is more useful in measuring everyday objects.

### Re: Mass of electrons

Posted: Wed Oct 17, 2018 5:33 pm
Just be aware that most of your SI units are in kilograms, because depending on the question, they may ask for an answer in grams. This won't always be the case, but it's good to be aware of the units in different measurements like joules and watts, it makes conversions much more clear.