D&D 5E Wherein we discuss spells and other magical things.

[Dannyalcatraz]

One of my first thoughts upon reading the description of ORS years ago was:

[video=youtube;g1eUIK9CihA]https://www.youtube.com/watch?v=g1eUIK9CihA&sns=em[/video]

But figured out they didn't mean exactly what they said.

 

[cbwjm]

All I can really add to this discussion is that there is no falling damage to an occupant of a resilient sphere in my games.

 

[jaelis]

All I can really add to this discussion is that there is no falling damage to an occupant of a resilient sphere in my games.

If a falling sphere hit you, would you get hurt? (If so, would the damage depend on the weight of the creature in the sphere?)

 

[cbwjm]

If a falling sphere hit you, would you get hurt? (If so, would the damage depend on the weight of the creature in the sphere?)

Honestly, I'm not sure the sphere would fall fast enough to hurt me, it would probably feel something like a balloon softly bumping into me. It says the sphere is weightless, I'm going to include the creature in the sphere with that. A halfling could easily pick up a sphere holding an ogre.

 

[Oofta]

"There is no "transfer" of energy from outside the sphere."

For the occupant to be damaged by the fall, there has to be.

Newton's 1st: "An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force."

When the ORS goes over a cliff, it's movement can only be affected by an unbalanced force. That is conveniently supplied by the ground.

The occupant has the same momentum as the ORS did, and normally, would follow the same rules. If the sphere were an unpadded concrete one, the physicist would say that the unbalanced force that stops the momentum of the occupant has the same source, the ground. The sphere acts as a conduit for the ground's application of an unbalanced force.

But the ORS explicitly prohibits this kind of transfer of energy.

The ORS isn't supplying the unbalanced force.

The inhabitant can't be the source of both the momentum AND the unbalanced force that stops him unless he's got thrusters.

The only source of the unbalanced force that stops the ORS and its inhabitant is the ground itself.

And the only difference between the ground impact and that of a weapon is amount.

The term energy in D&D is generally defined as lightning, fire, divine, necrotic, etc.

You're defining a game term "energy" in an entirely different fashion, and in a way that is not used anywhere else in the source books that I know of. Which is fine.

Unfortunately if you do that, if there can be no transfer of any energy then I don't see how the sphere can work as described. Externally it would be a mirror-like sphere. From the inside you'd be floating weightless in a black void (unless you had a light source in which case I'm not entirely sure what would happen since the interior of the sphere would probably be a perfect mirror).

If the sphere is moved, kinetic energy is transferred to the occupant or it is not.

If kinetic energy is transferred, the occupant moves with the sphere. Basic Newtonian physics applies and a sudden stop is going to hurt.

If kinetic energy is not transferred, and the occupant still moves with the sphere they can have no mass. With no mass, you are not affected by gravity and are effectively weightless. However if they have no mass they can't move the sphere. Since they can move the sphere, this cannot be the case.

In addition if no energy (of any type) cannot enter the sphere, you see a mirror ball and nothing inside. No one inside the sphere could see out.

If the sphere breaks physics in all sorts of ways that are not spelled then

• Kinetic energy is transferred from the sphere to the occupant when the sphere is moved.
• Kinetic energy is not transferred to the occupant when the sphere lands after falling from a cliff.
• Kinetic energy is not transferred to the occupant if you happen to be in Eberron and get hit by a lightning train.

I don't think that makes sense.

On the other hand, if you rule like @cbwjm, then the sphere and the occupant have no mass (and are therefore weightless) there is no falling damage. In a way that does make sense, except I don't see how the occupant could move the sphere if they weigh nothing. Well, and a strong breeze would send it flying. But it does seem more logical than the "sometimes kinetic energy is transferred and other times it is not".

 

[Cognomen's Cassowary]

I had considered this free-floating idea also, but the ability to "hamster" while in the sphere rules it out: it tells us gravity works within the sphere as normal (or else the occupant wouldn't be able to hamster around) which means a) the weight of the occupant holds the sphere to the ground and b) if there's no ground underneath, the occupant - and thus the sphere - are going to fall until there is.

Now, what happens if the sphere lands in water?

Lan-"I have this vision of a railway switching yard where the engineers are playing train-soccer with one of these spheres"-efan

You raise a good point, though it is not, strictly speaking, explicit in the spell description. Moving by pushing on the sphere's "walls" [I find the use of this word, in the plural, quite odd.] to roll it might not require a physical interaction with the ground; it might be a further magical effect of the spell.

Even given that gravity maintains its usual hold on the creature, if it, inside the sphere, does fall after rolling off a cliff, do we know that the sphere and character would accelerate? Or would they continue to move at the half-speed rate of rolling, constrained by the magic of the spell and limited in the kinetic energy that can be imparted to the occupant by the work of gravity?

Then, if they did accelerate, surely the airfoil of the sphere would factor into their rate of acceleration and terminal velocity, right? Using a handy online calculator (http://www.calctool.org/CALC/eng/aerospace/terminal), I find that the terminal velocity of the sphere, with the occupant's weight in it, would be around 25-30 mph. (I'm making assumptions using a medium-sized creature of 150 pounds). For comparison, via Wikipedia, the terminal velocity for a belly-down person is about 122 mph, depending on altitude and other factors, and for a person with a parachute, it's about 17 mph (about three times the speed of the feather fall spell). According to another handy tool (https://www.google.com/search?q=mph+to+km/h&ie=utf-8&oe=utf-8) 30 mph (or 48 km/h) would be reached under normal conditions by a person falling approximately 9.1 meters, or just about 30 feet. Thus if the sphere and content accelerate while falling, and if they fall far enough to reach terminal velocity, the occupant should take no more damage than he or she would by falling 30 feet under normal conditions.

There is one other unresolved aspect of the scenario, and that is what actually happens when the sphere strikes the ground (or some other surface). I find the hypothesis that the sphere would stop virtually instantaneously and the occupant would take falling damage as normal to be unsatisfactory. We know that the sphere is immune to all damage, and that physical objects cannot pass through the barrier. This means that the force of the impact will be transferred either to the sphere's contents or to the ground itself. We know that "a creature or object inside can’t be damaged by attacks or effects originating from outside," and the cause (gravity) leading to the effect (acceleration and impact) is outside the sphere. All of the energy of the impact, therefore, should go into the ground, and a small crater should be blown out until the sphere stops--or else the sphere should push the entire planet a minuscule distance--leaving the rider unharmed.

 

[Dannyalcatraz]

You're defining a game term "energy" in an entirely different fashion, and in a way that is not used anywhere else in the source books that I know of.

I know how the game defines "energy". All I am doing is using the term in its original sense to include kinetic energy- the source of damage from melee weapons- which we also know the sphere does not transmit:

and a creature or object inside can’t be damaged by attacks or effects originating from outside, nor can a creature inside the sphere damage anything outside it.

 

[Dannyalcatraz]

Except you aren't. Either the sphere and it's occupant can be moved (transferring velocity from outside the sphere to the occupant aka transferring kinetic energy) or it can't. If the occupant magically has no mass he could not hamster ball the sphere. He can, therefore he does.

D&D uses simplistic language. Energy in the D&D terms is lightning, fire, necrotic and so on. If literally no energy of any kind can be transferred to the occupant they would float weightless in the center of impenetrably black sphere until the spell ends.

The sphere's ability to be moved by the occupant or those on the outside is an explicit exception to its physics-defying abilities.

The sphere is weightless and just large enough to contain the creature or object inside. An enclosed creature can use its action to push against the sphere’s walls and thus roll the sphere at up to half the creature’s speed. Similarly, the globe can be picked up and moved by other creatures.

As for passage of light & sound, we know that the occupant can see and hear. But the ORS will not allow energy of those kinds though in lethal amounts.

This means that the force of the impact will be transferred either to the sphere's contents or to the ground itself.

Or, as I assert, the magic breaks the rules of physics and simply reduces the force to zero.*







* or, in a "magic is just physics we don't understand" setting, the kinetic energy is converted into magical energy, refreshing the source from which all casters derive their power.

 

[Satyrn]

Impossible, since the impact of hitting the ground cannot be transferred across the ORS barrier.

I think this sentence gets at the heart of the issue, describes excellently how you're seeing the scenario.

Let's see if I can describe why I think falling damage applies.

The sphere is falling and the occupant is also falling, a separate entity. The sphere hits the ground, and is undamaged, and the occupant is unharmed. But then the fellow inside is still falling inside the sphere. A mere fraction of a moment after the sphere hits the ground, the occupant hits the sphere and suffers tremendous pain.

 

[Dannyalcatraz]

I think this sentence gets at the heart of the issue, describes excellently how you're seeing the scenario.

Let's see if I can describe why I think falling damage applies.

The sphere is falling and the occupant is also falling, a separate entity. The sphere hits the ground, and is undamaged, and the occupant is unharmed. But then the fellow inside is still falling inside the sphere. A mere fraction of a moment after the sphere hits the ground, the occupant hits the sphere and suffers tremendous pain.

Again, the creature inside the sphere cannot be the source both of the momentum and the unbalanced force that stops him by simply falling. That is physics nonsense.

http://www.physicsclassroom.com/Class/newtlaws/u2l1d.cfm#balanced

A falling impact is- by definition- the falling object exerting a force on the surface it falls upon, and the surface exerting a force on the falling object.

But for the ground, there is nothing to exert that force upon the occupant- the ORS is merely in between.

Or to put it differently, if you asked a physics prof about the source of the unbalanced force that stopped a falling egg, and busted the yolk within (which would also likely shatter the egg, but that's not the issue), would he say it was the ground or the eggshell?