## Kg vs Grams

Sydni Stewart
Posts: 33
Joined: Fri Sep 28, 2018 12:29 am
Been upvoted: 1 time

### Kg vs Grams

Is there a reason we use kg in DeBroglie's equation? And in what other equations do we use kg as opposed to grams?

WilliamNguyen_4L
Posts: 65
Joined: Fri Sep 28, 2018 12:28 am

### Re: Kg vs Grams

We deal with Kg in DeBroglie's equation because in that equation we are dealing with momentum. Momentum is measured in kg*ms/s. We use kg in equations that deal with momentum, energy (Joules), etc. because those values are measured with kg in it. For example the units of joules is kg⋅m^2/s^2.

Danny Zhang 4L
Posts: 62
Joined: Fri Sep 28, 2018 12:26 am

### Re: Kg vs Grams

Within this class, I believe that we will only be using kg when dealing with energy and momentum.

Kevin Tang 4L
Posts: 83
Joined: Fri Sep 28, 2018 12:28 am

### Re: Kg vs Grams

It's kinda confusing that we use kg because all the other units we use don't use kilo. E.g. the SI unit for distance is meter, not kilometer; we use mols, not kilomols.

However, for mass, the SI unit is kilograms as other units use kg. E.g joules, which is measured in kg⋅m2⋅s−2.

Ariel Cheng 2I
Posts: 67
Joined: Fri Sep 28, 2018 12:29 am

### Re: Kg vs Grams

I think something that would help would be to write out the units for all parts of the equation. In h/mv, h is given in kg.m^2.s^-1. In order to cancel out the kg, the mass "m" needs to be in kilograms as well. The velocity should cancel out m.s^-1 and leave meters for λ.

Jchellis 1I
Posts: 61
Joined: Fri Sep 28, 2018 12:15 am

### Re: Kg vs Grams

Kg is an SI unit so always convert to Kg

AlyssaBei_1F
Posts: 99
Joined: Fri Sep 28, 2018 12:17 am

### Re: Kg vs Grams

Kg is the SI unit. We only use grams when working with moles. Always convert to kg.