Refrigerators are like rockets, right?

Click For Summary
A refrigerator's coils emit heat, which involves molecular motion, but this heat dissipates in all directions, resulting in negligible recoil forces on the appliance. The momentum lost through heat transfer is too small to overcome the friction holding the refrigerator in place, meaning it remains stationary. If the ground were exceptionally smooth, there might be slight movement, but various forces, including gravity and atmospheric pressure, keep it anchored. The discussion also touches on the conservation of momentum in a ballistic pendulum scenario, questioning whether heat loss affects momentum calculations. Ultimately, the consensus is that the heat's random dissipation does not produce a significant net force on the refrigerator.
  • #31
It can be. It's just not very efficient propulsion.

Maybe a flashlight is like a roman candle.
 
Physics news on Phys.org
  • #32
brainstorm said:
If radiation/light/infrared has momentum, why can't it be a source of propulsion without ejecting any kind of particle matter?
It can be - it just doesn't provide very much (as I discussed earlier).
 
  • #33
Antiphon said:
It can be. It's just not very efficient propulsion.

Maybe a flashlight is like a roman candle.

Maybe a roman candle is like a sparkler scaring away fireflies. These absurd analogies are fun. I think a whole section of the forum should be devoted to them. It would be like youtube without the videos.
 
  • #34
Antiphon said:
Maybe a flashlight is like a roman candle.
It is. In principle.
 
  • #35
DaveC426913 said:
It is. In principle.

Why, because they both send out discrete packages of luminosity that require chemical propellant to achieve subsonic velocity and then fade away after @50ft?

Or because they're both cylindrical and produce illumination?
 
  • #36
brainstorm said:
Why, because they both send out discrete packages of luminosity that require chemical propellant to achieve subsonic velocity and then fade away after @50ft?

Or because they're both cylindrical and produce illumination?

Because both produce thrust.
 
  • #37
DaveC426913 said:
Because both produce thrust.

Ok, let's assume you were trying to come up with a propulsion system that uses EM radiation. Obviously you want it as efficient as possible in terms of unit energy to unit propulsion. What would the variable parameters be for waste? Would there be certain wavelengths that would generate more thrust than others?
 
  • #38
brainstorm said:
Ok, let's assume you were trying to come up with a propulsion system that uses EM radiation. Obviously you want it as efficient as possible in terms of unit energy to unit propulsion. What would the variable parameters be for waste? Would there be certain wavelengths that would generate more thrust than others?

My post 34 consists of exactly 4 words. Of those 4 words, it seems I have the need to repeat two of them:

In principle.

:wink:
 

Similar threads

The reservoir of refrigerant between condenser & metering device
  • · Replies 7 ·
Replies
7
Views
2K
Evaporative cooling = refrigeration?
  • · Replies 2 ·
Replies
2
Views
2K
Pulling a vacuum on a heat pump with a recovery machine
  • · Replies 1 ·
Replies
1
Views
3K
I Is it possible to "violate" momentum at the expense of more energy?
  • · Replies 2 ·
Replies
2
Views
1K
Why ideal gases are not used in refrigerator?
  • · Replies 4 ·
Replies
4
Views
5K
A Few questions about how a refrigerator works
  • · Replies 13 ·
Replies
13
Views
4K
I Centrifugal Effects During Rail Launch
  • · Replies 3 ·
Replies
3
Views
1K
I An ID-card sliding on a low friction table
  • · Replies 14 ·
Replies
14
Views
2K
What is the Chemistry Behind Refrigerant Blends?
  • · Replies 6 ·
Replies
6
Views
4K
Could somebody please explain the vapor compression cycle?
  • · Replies 3 ·
Replies
3
Views
5K