## Prefix Conversion

$c=\lambda v$

AlyssaPeckham1A
Posts: 49
Joined: Fri Sep 29, 2017 7:04 am

### Prefix Conversion

When converting from a prefix such as nm into meters, should the conversion be before or after we solve the problem?

Jessica Lutz 2E
Posts: 56
Joined: Fri Sep 29, 2017 7:04 am

### Re: Prefix Conversion

I usually make sure to do it before the problem because most of the time throughout the problem you will be doing dimensional analysis with values that are in meters, not nm (such as velocity).

Sophia Kim 1C
Posts: 51
Joined: Fri Sep 29, 2017 7:04 am
Been upvoted: 1 time

### Re: Prefix Conversion

It depends on the problem! When you are calculating, the numbers should have the same prefix so in that case you would do the prefix conversion before the problem. (ex: if you are using the equation M=moles/L and you have to find the missing moles given M and mL of a solution you would need to do prefix conversion before by either changing the M to moles/ml or changing the given mL to L so that the "Liters" would cancel out and you would only be left with moles). Other times you would need to convert the prefix if the answer needs it to be in a specific unit so than you would just convert after you solved the problem (Ex: if a question asks for the nm of a wavelength and your final answer is in m you would need to do a prefix conversion at the end). I hope this makes some sense!!

Mikaila 3E
Posts: 21
Joined: Fri Sep 29, 2017 7:07 am

### Re: Prefix Conversion

Sophia brings up a good point. For me, I think it's up to you and how you prefer to see your numbers/units. I tend to convert my units at the beginning so I don't forget to convert them at the end after all the calculations have been made.

Golbarg Rahimi 3k
Posts: 26
Joined: Sat Jul 22, 2017 3:01 am

### Re: Prefix Conversion

Hi
I tend to convert all the units into SI units or to common chemistry units ( s , m, g) before trying to solve the problem. After the problem has been solved, I convert them back to the desired units in the problem.

MichelleT_1L
Posts: 20
Joined: Fri Sep 29, 2017 7:04 am

### Re: Prefix Conversion

It is the easiest to convert first so you don't forget throughout the problem to convert. At the end you can convert back to the units that the question asks for but throughout the problem if there are different units, using meters, seconds, or kilograms is a basic standard unit to use.

Janet Nguyen 2H
Posts: 51
Joined: Fri Sep 29, 2017 7:05 am

### Re: Prefix Conversion

I would convert in the beginning or right when you are doing the problem. It would be best to have the same units so that they can properly cancel out. Doing so, you will be seeing that you end up with the right units in your answer.

Peri Bingham 1G
Posts: 50
Joined: Fri Sep 29, 2017 7:03 am

### Re: Prefix Conversion

I prefer to convert my units in the beginning based on the questions and the formulas being used in the question. At the end of the problem, I make sure that my answer is in the proper units which may involve more converting. In this chapter, I tend to see myself doing this a lot in regards to wavelength and the conversion between nm and m.

Jasmin Tran 1J
Posts: 54
Joined: Thu Jul 27, 2017 3:00 am

### Re: Prefix Conversion

Like the posters above, I normally convert after or as I'm doing the problem. Say I'm starting with 5.5 kg of Al, I would convert to g or whatever units the question is asking for first so that I don't get confused at the end. Plus, it makes the work neater if you have it with dimensional analysis.

Angel Ni 2K
Posts: 50
Joined: Sat Jul 22, 2017 3:01 am

### Re: Prefix Conversion

I will usually convert the nm into m first because most ratios use m (such as speed of light). After I finish solving the problem, I make sure that the answer is in the units that the question asks for. If the question does not satisfy, I will usually just leave it in meters.

Posts: 51
Joined: Fri Sep 29, 2017 7:07 am
Been upvoted: 1 time

### Re: Prefix Conversion

I would say to convert the problem to whatever the other variables are, so if you have meters in one and nm in another then convert both to meters to solve it and once solved, then put it back into what its asking or meters.

peytonruiz 1H
Posts: 20
Joined: Fri Sep 29, 2017 7:03 am
Been upvoted: 1 time

### Re: Prefix Conversion

I agree. It depends on the problem and the information given. However, usually, I convert before the problem because usually information/constants are given in meters :-)

nanditasundarapandian1D
Posts: 21
Joined: Sat Jul 22, 2017 3:01 am

### Re: Prefix Conversion

I think it just depends on the specific problem and your preference!