Question

An air conditioner removes 4.6×10^5 J/min of heat from a house and exhausts 7.8×10^5 J/min to the hot outdoors. How much power does the air conditioner's compressor require?

Answer 1

So I'm not really sure where to start with this problem. Energy isn't heat so... yeah.

Answer 2

*pokes through for useful equations that might relate*

Answer 3

What are you looking for?

Answer 4

are you looking for efficiency?

Answer 5

Where to start... oops, question is "How much power does the air conditioner's compressor require?"

Answer 6

I don't know what that means or how it relates to the "joules of heat" in the air. It seems weird to me.

Answer 7

What are the units of value above?? Joule? or Calory?

Answer 8

Um, they're in J/min. :6

Answer 9

Ah! I didn't mean to close the question... I was just fixing what it said... (I don't use this site much.)

Answer 10

I fixed it.

Answer 11

using P = W/t., where P is Power, W is work, and t in time

Answer 12

W is also Heat, work and so on..,

Answer 13

Okay, so the work is the heat removed? Does the exhaust cost anything work wise?

Answer 14

P = ((4.6×10^5 (+ MAYBE 7.8×10^5))*60)/t ~ I'm not sure what t is in this case but I feel like this should result in a rate or something like s^-1/Watts

Answer 15

i think that's addtion of both

Answer 16

Multiplying the top by 60 converts the minutes to seconds, seems reasonable.

Answer 17

work=7.8*10^5

Answer 18

so...., if @03225186213 is right.., P is W/t = (7.8*10^5/ 60s) Watt

Answer 19

So W would be the J/min exhausted into the environment by that logic. It seems like the units aren't properly preserved.

Answer 20

The joules need to be eliminated somehow.

Answer 21

Can't just drop things... Watts should be s^-1, so the joules need to be eliminated in the formula or by a conversion factor. Assuming power is in Watts.

Answer 22

s^-1 is frekuensi...., do you remember f = n/t ??

Answer 23

i mean frequency is s^-1.., sorry

Answer 24

No... I don't remember. f = n/t Is f frequency? t is definitely time.

Answer 25

yes f is frequency...,

Answer 26

AH! You're right! Watts are J/s and Hz are s^-1. (Feels a lot less confused)

Answer 27

yes another unit of frequency is s^-1 and J/s for Watt

Answer 28

So I just need to convert the energy taken to make the air cool, that is the exhausts and convert it into Watts. Wow. That's significantly less confusing.

Answer 29

Which would be... 46,800,000 W? (That doesn't seem right...)

Answer 30

Hm.... Maybe energy in - energy out?

Answer 31

Nope... -_- What's t?

Answer 32

maybe that is eficiency where in/out times 100%

Answer 33

Efficiency's the next part, but I didn't have any trouble with that part of my homework. It should just be work in/work out.

Answer 34

Well 1 - that.

Answer 35

So maybe that means power in this case is just work? Since we're assuming it's perfectly efficient?

Answer 36

Except... it's not.

Answer 37

that's work per sekon, so that's power..., It's just that in the view of work

Answer 38

I wanna say
4.6×10^5 J/min + 7.8×10^5 J/min
And if you want it in watts just convert from J/min to j/ s

Also I think capital J means thousands where as j is just a joule

Answer 39

Sekon isn't a unit I'm familiar with...

Answer 40

yes i think so @timo86m ...,

Answer 41

sory i mean seconds

Answer 42

Ah, that explains why I was so confused. ^_^

Answer 43

20667 W doesn't work....

Answer 44

may I see your question paper?

Answer 45

It's not on paper. :P Question posted is all there is. It's online.

Answer 46

So the top is all the information given.

Answer 47

So what's your choice?

Answer 48

What do you mean choice?

Answer 49

The choice is to keep working on it or not... I'm thinking about it and experimenting with my given values...

Answer 50

I guess I'll just work on it offline though. I don't seem to be making much progress online. I'm sorry I bothered you guys.

Answer 51

it's your decision ^^

Answer 52

kk

Answer 53

hey you no bother at all :)

Answer 54

Ahahaha! I figured it out! It was work out - work in! =D

Answer 55

that is odd

Answer 56

Nah, it makes sense. :) It's doing work on the air so the air's energy doesn't count towards the energy used by it being plugged in.

Answer 57

i got 20666.66667 watts
or 20.666 Kilo watts sounds reasonable

Answer 58

Yup, that's what you get if you add them. The energy in the air makes it so the electricity doesn't have to do as much work.