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### Units

Posted: Thu Oct 18, 2018 11:38 pm
What unit does J.s^(-1) translate into, and how would we use this new unit to calculate the correct unit for finding wavelength, in say, the equation of λ=h (unit of J.s^(-1)/mv?

### Re: Units

Posted: Thu Oct 18, 2018 11:40 pm
It translates into kgm^2/s because a joule is kgm^2/s^2, and if you divide it by 1/s, it gets to this unit.

### Re: Units

Posted: Sun Oct 21, 2018 1:32 pm
1 joule = 1kg·m^2·s^-2
If you divide it by s-1. One of the 's' cancels out and you get 1kg·m^2·s^-1.

### Re: Units

Posted: Sun Oct 21, 2018 9:14 pm
Its important to remember that we use kg instead of grams for SI units. I know I always forget!

### Re: Units

Posted: Mon Oct 22, 2018 12:19 am
Joule is kgm^2/s^2, but multiplying my 1/s cancels one of the s units, making kgm^2/s

### Re: Units

Posted: Mon Oct 22, 2018 2:55 am
Just another reminder too is that Herz = s^-1. I find it helpful to convert Hz to s^-1 so that if units are being multiplied or divided, it's easier to see how things cancel out.

### Re: Units

Posted: Thu Oct 25, 2018 10:13 am
a Joule multiplied by 1/s is composed of 1kgm^2/s in its simplest form

### Re: Units

Posted: Thu Oct 25, 2018 7:36 pm
When do we use kg?

### Re: Units

Posted: Thu Oct 25, 2018 8:07 pm
105002507 wrote:When do we use kg?

We use kg when we are calculating energy, since the units are in jules (kg·m^2·s^-2)

### Re: Units

Posted: Thu Oct 25, 2018 11:14 pm
It should follow e=mc^2 for photons, which is kgm^2/s^2

### Re: Units

Posted: Sun Nov 04, 2018 11:28 pm
If a calculation is in Hz, does that mean it will always be a positive value?

### Re: Units

Posted: Fri Oct 11, 2019 9:26 am
Do we need to know the SI unit equivalents for each term, like the joule?

### Re: Units

Posted: Fri Oct 11, 2019 7:03 pm
Kelvin Chung 1C wrote:Do we need to know the SI unit equivalents for each term, like the joule?

I am not sure if you need to know them, but for the quantum section it would extremely helpful to know that a J is equal to kg*m^2*s^-2

### Re: Units

Posted: Fri Oct 11, 2019 8:08 pm
I'm sure that it is important that you know the proper SI units for each term because there will be many problems which can be solved by canceling out, thus helping you find a corresponding answer for that problem in the simplest form.

### Re: Units

Posted: Sun Oct 13, 2019 3:23 pm
Will there ever be a time where we need to use megagrams or gigagrams or will we likely only go as big as kilograms?

### Re: Units

Posted: Sun Oct 13, 2019 4:46 pm
I think for the most part it would only go as far as kilograms, but in any case, if megagrams and gigagrams were necessary I think we would be provided a formula sheet to convert the numbers.

### Re: Units

Posted: Sun Oct 13, 2019 5:00 pm
If you ever forget unit conversions just remember:

K- King
H- Henry
D- Died
U- Unusually
D- Drinking
C- Chocolate
M- Milk

### Re: Units

Posted: Wed Oct 16, 2019 3:35 pm
Is it necessary that we put in the units while showing our work?