J vs. kJ

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Katie Frei 1L
Posts: 64
Joined: Fri Sep 28, 2018 12:27 am

J vs. kJ

Postby Katie Frei 1L » Wed Jan 30, 2019 2:16 pm

When considering the units for work, are we supposed to give our final answer in J or kJ? Thanks!

Rachel-Weisz3C
Posts: 66
Joined: Fri Sep 28, 2018 12:23 am

Re: J vs. kJ

Postby Rachel-Weisz3C » Wed Jan 30, 2019 2:20 pm

I think problems will normally specify what ids preferred or if they give you a value with J or kJ included, use the one that is given. Otherwise you should be able to do either and just make sure the units are present.

Danielle_Gallandt3I
Posts: 70
Joined: Fri Sep 28, 2018 12:24 am

Re: J vs. kJ

Postby Danielle_Gallandt3I » Wed Jan 30, 2019 2:28 pm

I don't think there is a specific rule but I think it might jus be what makes more sense for that problem. For example, if it is a really big value it would make more sense to have units in kJ rather than J. I think unless it specifies it in the question it will probably be up to your own discretion.

dgerges 4H
Posts: 65
Joined: Fri Sep 28, 2018 12:24 am

Re: J vs. kJ

Postby dgerges 4H » Wed Jan 30, 2019 3:06 pm

J is the SI unit, but if the rest of the problem is worked out in kJ then probably use that. on tests they'll probably specify

JiangJC Dis2K
Posts: 72
Joined: Fri Oct 12, 2018 12:16 am

Re: J vs. kJ

Postby JiangJC Dis2K » Wed Jan 30, 2019 3:27 pm

Work=-pressure*change in volume. The units for that are kgm-1s-1m3. The meters cancel out through exponent rules to create the unit kgm2s-2. This equals a joule. Therefore, your answer should be in joules, unless all other units in the equation are multiplied by 1000. But you could convert the final answer after you have found it to kJ if it is most convenient.

Hannah Pham 1D
Posts: 62
Joined: Fri Sep 28, 2018 12:19 am

Re: J vs. kJ

Postby Hannah Pham 1D » Wed Jan 30, 2019 11:53 pm

It shouldn't matter unless they specify! Make sure you know what the question is asking though.

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

Re: J vs. kJ

Postby gwynlu1L » Thu Jan 31, 2019 3:51 am

I would think you would usually just stick to the units given already in the problem, unless specified otherwise. although, it may be better to use J because it is the SI unit and in calculations.

Jasmine Chow 1F
Posts: 60
Joined: Fri Sep 28, 2018 12:16 am
Been upvoted: 1 time

Re: J vs. kJ

Postby Jasmine Chow 1F » Thu Jan 31, 2019 10:55 pm

It depends on what the problem specifies. If it does not ask I usually keep the answer in the units the problem gave the values as.

Millicent Navarro 1I
Posts: 61
Joined: Fri Sep 28, 2018 12:25 am

Re: J vs. kJ

Postby Millicent Navarro 1I » Fri Feb 01, 2019 1:18 am

It depends on what the question is specifically asking. However, it is crucial to make sure that as you are solving a problem, all the units are consistent (i.e., if you are using just Joules, make sure it is just Joules.)

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

Re: J vs. kJ

Postby Danny Zhang 4L » Fri Feb 01, 2019 1:37 pm

J is what is most commonly used to represent work. We can of course use kJ to represent work as well when specified by the problem.


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