## Mass of electrons

$\lambda=\frac{h}{p}$

Marsenne Cabral 1A
Posts: 59
Joined: Fri Sep 28, 2018 12:19 am

### Mass of electrons

When calculating the mass of an electron, why is the SI unit in kg and not grams? Wouldn't grams make more sense?

Ray Guo 4C
Posts: 90
Joined: Fri Sep 28, 2018 12:15 am

### Re: Mass of electrons

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.

MaggieMatern_Dis1H
Posts: 30
Joined: Fri Sep 28, 2018 12:19 am

### Re: Mass of electrons

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.

Nicole Lee 4E
Posts: 60
Joined: Fri Sep 28, 2018 12:16 am
Been upvoted: 1 time

### Re: Mass of electrons

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.

gwynlu1L
Posts: 62
Joined: Fri Sep 28, 2018 12:19 am

### Re: Mass of electrons

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.