Can you cool off the kitchen by leaving the refrigerator door open?

In summary, the man walking on a tight rope with the help of a balance bar may be better off using a straight or bendy bar, while a refigerator uses energy from the wall plug to cool down the kitchen. The heat pump part of the machine takes energy input to work, so if you have a perfect refrigerator, opening the refrigerator door won't do anything.
  • #1
AzMaphysics
19
0
Alright, I'm stuck on a few problems with a physics brain teaser sheet.

1. Suppose you have a very small kitchen with a refrigerator. Can you cool off the kitchen by leaving the refreigerator door open?
2. Which bracing for a screen is strongest: two vertical bars, one horizontal bar crossing vertical bar, one diaganol bar, or a vertical bar.
3.A man is walking on a tight rope with the aid of a balance bar. Is a long or short bar better? Is a light or heavier bar better? Is a straight or bendy bar better?

The last two I think I know, but the first one I'm not exactly sure.

I know these seem dumb but can someone please respond.
 
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  • #2
Not dumb at all, and welcome to PF, Arizona!

-1- Do you know how a refigerator works? It's basically a heat pump. And it consumes energy from the wall plug, right? What does that mean?

-2- and -3- you already have.
 
  • #3
Well I thought that it would cool down the kitchen until it reached an equilibrium but that seemed almost too obvious of an answer.
For 2, I originally thought the diagonal one would be best because it creates two triangles but then I figured the the crossing one would be more stable.
For 3, I thought a long, heavy, and bendy bar would be best
 
  • #4
Perfect on 2 and 3. What can you say about a "heat pump" on 1?
 
  • #5
Ok I think i get why it might not cool down the kitchen but I can't put it into words. Doesn't the heat pump somehow move the thermal energy from the refrigerator into the kitchen. Then if you just opened the refrigerator it wouldn't do anything but i can't explain that part.
 
  • #6
The heat pump part is about how you can make a machine to pump thermal energy from one place to another, but it takes energy input to make that pumping happen. You're real close to understanding the answer to your homework question. Try a wikipedia search on refidgerator or heat pump to finish off your research.

EDIT -- apologies for any misspellings.
 
  • #7
Ok so I'm still not sure I have the answer. Is it because originally, before the heat pump starts to work, the area inside the refrigerator and the area outside are at equal temp but once the heat pump begins to work the refrigerator area gets cooler but makes the outside area somewhat warmer. Now here is where the question comes in. You open the refrigerator door, the area on the outside cools back down to the original temp and the area inside warms back up to the orignal temp. I don't i still think I'm wrong.
 
  • #8
Definitely wiki refridgeration:

http://en.wikipedia.org/wiki/Refridgeration

and maybe heat pumps as well. A 100% efficient heat pump will pump heat energy from one place to another. A more real heat pump will take energy in and pump some delta-E from one place to another (like from the inside cooling air in a 'fridge to the hot coils on the exterior back of the 'fridge). A non-100% efficient heat pump will add extra waste heat...
 
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  • #9
AzMaphysics said:
Ok so I'm still not sure I have the answer. Is it because originally, before the heat pump starts to work, the area inside the refrigerator and the area outside are at equal temp but once the heat pump begins to work the refrigerator area gets cooler but makes the outside area somewhat warmer. Now here is where the question comes in. You open the refrigerator door, the area on the outside cools back down to the original temp and the area inside warms back up to the orignal temp. I don't i still think I'm wrong.
If you have a perfect refrigerator, that sounds about right, the question is do you have a real refrigerator, or a magical device for moving heat from one place to another? (I don't know this, it is outside of your description).
 
  • #10
Well I read them both, and I'm still not sure. Heat and thermodynamics have always been a weak spot for me and the fact that I'm trying to convert 2007 into all bases up to 13 probably doesn't help. I'm guessing the answer is no but have no definitive proof to explain why. At 11:00 at night (i live in Ma), wikipedia is just plain out confusing.
 

What happens if you leave the refrigerator door open?

Leaving the refrigerator door open can result in warm air entering the fridge, causing it to work harder to maintain a cool temperature. This can lead to increased energy consumption and potentially spoilage of food.

Can leaving the refrigerator door open cool off the kitchen?

Leaving the refrigerator door open will not effectively cool off the kitchen. While the open door may release some cool air into the room, it is not enough to significantly lower the temperature.

Is it safe to leave the refrigerator door open?

Leaving the refrigerator door open for a short period of time is generally safe, but it is not recommended as it can impact the performance and efficiency of the fridge. Additionally, if left open for an extended period, it can lead to food spoilage and potential safety hazards.

Will leaving the refrigerator door open damage the fridge?

Leaving the refrigerator door open can cause damage to the fridge by making it work harder and potentially leading to mechanical issues. It is important to always close the door to maintain the proper temperature and functioning of the appliance.

How can you cool off the kitchen without leaving the refrigerator door open?

To effectively cool off the kitchen, it is best to use alternative methods such as turning on a fan, opening windows, or using air conditioning. These methods are more efficient and will not impact the performance of the refrigerator.

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