Force Field Experiments: Realistic Physics Questions

In summary, the force field would be very unstable and would likely tip over if placed on a sea ship's deck. Depending on the properties of the field, it might cling to a surface or fall over.
  • #1
Flannel
5
3
Hello everyone!

Events in my current webnovel have reached the limit of confidence in my physics reasoning, so I'm here to ask for confirmation of my estimates of what would happen from experimentation with force fields. While the setting is fantasy/magic based rather than superscience, I still want to maintain as much realism as I can.

Tools currently in use:

WolframAlpha Ideal Gas Law
Aqua-Calc volumes to weight conversions

Current questions:

1) Assuming a force field of
  • negligible material mass
  • with dimensions of 1m x 4m x 9m, for 36 cubic meters volume (yes, a metric scaled 2001/Space Odyssesy Monolith)
  • filled with room temperature air at 1 atmosphere, thereby
  • massing/weighing 46.54 kg -

how would this object react to an unsteady surface - specifically, resting on the deck of a docked sea ship?

How easily would it tip over? Since it contains an amount of air equal to what it displaces, I have the amateur impression that it would be very unstable.

What would happen as it fell over? My amateur impression, again, is that some of its radial downward momentum would be converted into forward gliding as it closely approached the deck, due to compression of the air beneath against said deck, while dragging its back bottom edge along that surface. Am I correct?

2) When calculating ideal gas law changes, does a decrease in the size of the volume not alter the original pressure constant within the container? That's what I think has been tripping me up when I try to calculate the temperature increase of the air inside when the main character shrinks one of these force fields.

3) More generally, how would a decrease in volume to 20% of the original force field affect the air inside it?

Any help will be gratefully appreciated!
 
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  • #2
Hello @Flannel,
:welcome: ##\qquad## !​

Flannel said:
How easily would it tip over?
Tip over into what ?

##\ ##
 
  • #3
1) As long as the force-field itself doesn't mass anything, and the internal density is the same as external, it's not going to "rest on" anything, nor "fall down". Think a toy balloon with just enough Hydrogen in it that it floats. You've still got some 100lb of inertia, though.

Depending on the properties you give the field, you might get it to stick to a surface.
 
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  • #4
BvU said:
Tip over into what ?

##\ ##
Thank you for the welcome!

Tip over onto the deck below.
 
  • #5
hmmm27 said:
1) As long as the force-field itself doesn't mass anything, and the internal density is the same as external, it's not going to "rest on" anything, nor "fall down". Think a rubber balloon with just enough Hydrogen in it that it floats. You've still got some 100lb of inertia, though.

Depending on the properties you give the field, you might get it to stick to a surface.
Thank you for replying!

So for it to settle, I could make the mass of the barrier "material" itself non-negligible instead, right?

I can work with that. In fact it will probably even make things easier on me going forward, since I'll have to set constants for barrier durability relative to thickness just to begin with. Then I can use those for mana expenditure calculations.

Baseline max resistance of five atmospheres would be 73.5 psi, which is. . .between half and 2/3rd average human punching force. Yes, good! Not too strong, but that should scale well.

Your response is very helpful; thank you!
 
  • #6
Aaaah! Where did the other reply about volume/temperature go? Noooo! That one was super helpful too! I didn't imagine it, right?

I still have to figure out all sorts of things about heat/cold/pressure/vaccuum damage potential!

Come back to me! Please!
 
  • #7
Flannel said:
Tip over onto the deck below.
I am afraid I don't understand. Wouldn't the air on the deck below be in the way somewhat ? Or does this all take place in a vacuum ?

##\ ##
 
  • #8
Flannel said:
Aaaah! Where did the other reply about volume/temperature go? Noooo! That one was super helpful too! I didn't imagine it, right?

I still have to figure out all sorts of things about heat/cold/pressure/vaccuum damage potential!

Come back to me! Please!
Here are three ways to look at the problem. Let V=V0/a. I have implicitly assumed that T0 is equal to the external-to-the-field air temperature. A “fast“ compression will look adiabatic.
1) Isothermal compression (air temperature does not change): In this case the relevant equation is PV=kT=constant
PV/P0V0=1
P=P0V0/V
P=aP0
2) Adiabatic compression (there is no heat flow). In this case the pressure is determined by
PVϒ=constant=P0V0ϒ
P=P0(V0/V)ϒ=P0aϒ
for air ϒ=1.4
Now use PV=kT
PV/P0V0=T/T0
T=T0aϒ-1 (T is measured in Kelvin)
for air initially at room temperature (298K) and a=5 (volume compressed 80%)
gives T=567K= 561°F
3) You could control the amount of heat flow to let T vary from T0 to the adiabatic temperature. In this case, use
PV=kT
PV/P0V0=T/T0
P=aP0T/T0
 
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  • #9
BvU said:
I am afraid I don't understand. Wouldn't the air on the deck below be in the way somewhat ? Or does this all take place in a vacuum ?

##\ ##
Yes, the air below it would. In case you're asking about its expansion from a central point, the generation of the field's 6 connected surfaces is effectively instantaneous in all axes. So the field was generated already resting on the ship's deck - er, stage, that is - below.

And yes, it's happening in a big room. The main character's doing his testing on the stage of the Theater on the maindeck, in the hull's largest area, i.e. under the weather or lowest exposed surface deck.

I'd forgotten about the effective air-buoyancy issue, which is rather embarrassing considering I just had a supporting character figure out lighter-than-air flight from a mere few hints several chapters earlier.
 

Related to Force Field Experiments: Realistic Physics Questions

1. What is a force field in physics?

A force field in physics is an invisible area around an object or particle that exerts a force on other objects or particles within its range. This force can be attractive or repulsive, and is caused by the presence of a field, such as an electric or magnetic field.

2. How does a force field affect objects?

A force field affects objects by exerting a force on them. This force can cause objects to move, change direction, or deform. The strength and direction of the force depends on the properties of the object and the type of force field present.

3. What are the different types of force fields?

There are several types of force fields in physics, including electric, magnetic, gravitational, and nuclear force fields. Each type of force field is caused by a different fundamental force and has its own unique properties and effects on objects.

4. How is a force field measured?

A force field is measured using a variety of instruments and techniques, depending on the type of force field being measured. For example, an electric field can be measured using an electric field meter, while a magnetic field can be measured using a magnetometer.

5. What are some real-life applications of force field physics?

Force field physics has many practical applications in our daily lives, such as in the design of electronic devices, medical imaging technology, and the development of renewable energy sources. It also plays a crucial role in understanding and predicting the behavior of particles and objects at the atomic and subatomic level.

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