Natasha wrote:You've missed a critical point in all the websites you've posted about relative motion so far.
Two trains are standing beside one another in a station and one starts to move.
That quote is the
first sentence of the section on relative velocity. To say that two trains are
standing, we must have first measured their velocities with respect to the surface.
The concept of "standing beside one another" means they have no difference in velocity as it pertains to the other.
"in a station" is the point of reference, not "the surface".
The first sentence of the paragraph on relative velocity starts off exactly like Rifts rules do, exactly as you did with your 100 mph train, and exactly as you did with your 1500 mph grunts.
Natasha wrote:If you use the Shooter as the reference point to give velocity meaning, you must assert that the Shooter is inertial, which means its velocity never changes because it defines the standard of measure. Good luck with that.
Velocity is fixed at any given point in time.
Are you trying to comment on how speed could change between the time a bullet is fired and when it reaches its target?
That's a valid concern, if so. Particularly with very long-range combat and missiles which might take several melee rounds to get to a destination.
Natasha wrote:If no reference is mentioned, it is normal to assume that all velocities are measured with reference to the stationary ground.
That is from one of your sources. Think about it and then about what you claim should be assumed when no reference is given, and consider the difference. Your source disagrees with you.
The source does not disagree with me, because we have 2 reference points already: attacker and target.
Natasha wrote:The two trains are moving along parallel paths, and it is an easy matter to calculate the velocity of one relative to the other, provided their velocities relative to the ground are already known.
Go back to the sentence describing what gives velocity meaning. What makes the direction component of their velocity parallel? What makes that a true statement? What gives it any meaning at all? The answer is given: "their velocities relative to the ground are already known".
Knowing direction relative to ground is not required to calculate direction relative to each other.
Natasha wrote:Assuming a steady walking speed of u meters per second (relative to the train, of course), the walker will see the front clock to read L/u seconds on arrival there.
That source felt it was important to make the distinction because it's "common sense" and "normal" to think of velocities in terms of the surface.
To the contrary: this says "of course" meaning it is reminding people to use established context, not to resort to archaic thinking.
Natasha wrote:It actually says that it's necessary:
Hence it is necessary to do a careful analysis of a fairly speedy person moving from the back of the train to the front as viewed from the ground, to see how velocities really add.
What all of this adds up to is: use the surface.
Only if you are told to calculate velocity in respect to the surface, which Rifts doesn't do.
Natasha wrote:True, Earth is rotating and it's orbiting, which is why I said the surface is "approximately inertial". That's a term you'll encounter the more you study physics; I didn't make it up.
Earth is not the only platform which can endow approximate interiality between passengers.
Natasha wrote:The associated speeds, as you correctly point out, are large. But the associated accelerations are small enough to be ignored for motion problems like ours. And it's acceleration that matters (see Newton's first and second laws of motion).
I would be glad to acknowledge acceleration where Palladium says to apply it, but that doesn't appear to be here.
As I referenced earlier though, in acknowledgement of changes in velocity over time and how melee attacks generally would have a delay between attack-launch and attack-land, perhaps the fairest thing to do would be to average out start/end velocities and apply penalties based on the average.
Natasha wrote:Axelmania wrote:A pair of CS grunts are taking a ride inside the same 1500mph Death's Head Transport. ... Now if you ditch your house rule about "relative to Earth" velocity and use the most logical reading of this (velocity relative to attacker) it would be 0 (they're not moving toward or away from one another) and there would be no penalty to shoot the guy sitting next to you on the Death's Head Transport.
Look at how you are arriving at 0. You find Shooter Grunt's velocity then Target Grunt's velocity then subtract. You are measuring their velocity with reference to the surface first so that you can perform the vector operation to find their relative velocities.
The earth is only one example of a reference point. You can also calculate it directly from the Death's Head, or from a 2nd Death's Head following a mile behind.
Natasha wrote:Axelmania wrote:Good judgment leads to discerning it means speed between the two established things within that action: shooter and target.
It has been made abundantly clear that the "speed between the two established things" requires both speeds to be "measured with reference to the stationary ground" first. You couldn't give either your train or grunt example without doing precisely that first. Look at how you "established" them.
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Who "requires" this, exactly? You can measure speed between 2 things based on a satellite or a helicopter instead of the ground if you want to.
eliakon wrote:And they have a velocity of 0 because the local velocity is calculated by looking at how fast they are moving in regard to the frame of reference.
In this case the death head that they are both inside of is the frame, and thus they have a velocity of 0 each.
This is why when you take a shot at a person in the game, you do not add in the earths velocity around the Sun, nor the Sun's velocity around the Milky Way, nor the Galaxies movement ad infinitum.
The frame of reference for the game is more or less "this play area here" regardless of if that is the earth, or inside some ruins, or on a space ship or what have you.
I'm not disagreeing with you at all.
My point is moreso that you don't have to have an actual object representing the "play area", because that simply is an explanation for why people aren't gradually drifting apart due to differences in air resistance.
Two people sitting side-by-side in a DHT are just as 0 as two people riding side-by-side in hovercycles.
Blue_Lion wrote:Axlemania you are keep are ignoring 1 the common use of the term 2 how your sources says speed is commonly measured. Think about it this way a vehicle has a top speed of 200 MPH. If there is no default refence point for speed that stat has no inherent value.
The default reference point is the location of your vehicle at a previous point in time.
Blue_Lion wrote:By your no default chased if a jet a speed max speed of 500 MPH was to chase a vehicle with a max speed of 200 MPH the vehicle being chased would never be caught because it would it would have a speed relative to the vehicle chasing it of 200 MPH.
I never said that speed relative to opponent applied outside of attack penalties, enough strawmanning.
Blue_Lion wrote:How do you know in your example that the death head transport is traveling at 1500 MPH how was the speed of the death head transport determined?
Relative to its previous position.
Blue_Lion wrote:Oh wait you used the common method of measuring speed relative to the ground.
Wrong. If I had to say it was in respect to anything I would say relative to a position within the atmosphere, since it is inheriting the atmosphere's momentum of rotation and solar orbit.
Blue_Lion wrote:The rule is traveling X MPH, not traveling X MPH relative to the attacker.
"Traveling Xmph" is always relative to something. The frame of reference in the case of attacks is attacker and target, not target and Brittania or whatever landmass you're wanting to grab onto.
Blue_Lion wrote:That means you use the default method to give a speed stat value. (relative to the ground.) So I am not using a house rule, but you are using flawed logic to disprove a known standard.
Whatever in the books might lead you to think this is the default is overriden by the context of attacks introducing a necessary point of reference: the attacker.
You're trying to determine whether an attacker can get a projectile to the target, not whether a target can get to their destination.
Blue_Lion wrote:what makes the death head the default frame when the death heads speed is detrimed by another frame so every thing in the death head exists in the same frame that the death head is. The reason we do not include the rotation of the earth in speed is the default way speed is commonly measured is in relation to the surface. Not because of your theory on limiting the frame.
THE MEGAVERSE does not have a default frame of reference. Indefinite articles only mean something when context is present. The context of shots fired is shooter and target, not target and some point on the averaged circumference of the spherish Rifts Earth.
Blue_Lion wrote:The rule says is the speed the target is traveling at, not velocity, or speed relative to the attacker. People inside a vehicle that is traveling are traveling, even if the are not moving under their own power.
People sitting inside Earth's atmosphere are also traveling, even if they are not moving under their own power. Thus concepts like "Spaceship Earth". Whether you are "traveling" is entirely specific to what frame of reference is used.
There is no reason for that frame of reference to be assumed to be Rifts Earth. If so then someone stationary on Mars is always "traveling" because the distance between them and Rifts Earth is always changing. Someone on the moon is also always "traveling" even if they remain stationary on the moon, because you INSIST that the frame of reference be Rifts Earth.
This is your house rule. We are never told the frame of reference must be Rifts Earth. The only frame of reference guaranteed to exist is the attacker. The only thing that matters is the rate at which the distance between attacker and target is changing over time in the "instant" the attack occurs.
(putting that in quotes since of course, attacks are rarely TRULY instantaneous so some specific point during an attack like launch/arrival might need to be chosen)
Blue_Lion wrote:So both dead boys are traveling at 1500 MPH, because the are on a vehicle that is considered to be traveling at 1500 MPH. (there is a default frame used to give speed stats a value.) While they may have a relative velocity of 0 to each other, there is a default way to determined speed is based of the surface of the earth.
The default you have house-ruled and which is not present in the book.
Blue_Lion wrote:The DB in a moving vehicle always has a velocity, that is why they can get injured in a crash.
If you are referring to RUE 356's similar 1D4 per 50mph above 20mph, that is clearly also velocity in respect to whatever it is you're crashing into.
If a SAMAS and Flying Titan speed away from a starting point at 300mph/290mph any minor bumps they have into the other would be 10mph.
Blue_Lion wrote:The vehicle you are in is not the limit to the frame you are in, but how you are traveling through the frame you are in.
Frame of reference is not fixed, it is mutable.
Blue_Lion wrote:Basically the death head is using speed relative to the ground (default value of speed) so every thing inside the death head is in the same frame as the death head, and traveling in the death head, even if they are not moving. Because that is how speed and traveling is commonly measured. (people are getting so caught up in physics the are forgetting how people commonly talk about speed and traveling.)
Kevin Siembieda is not a commoner. He's a smart guy.
Blue_Lion wrote:(people are so caught up with principles of physics they are forgetting the basics of how speed is talked about and commonly measured. Rifts is not written in physics but in the way people commonly talk about things.)
People "commonly" don't even use numbers to measure speed, they'll just say "fast" or "slow".
Unless you can point out somewhere where Siembieda insists on using Rifts Earth as the universal frame of reference in the Megaverse, you don't have a leg to stand on.
If you have a copy of Heroes Unlimited 2nd Ed, check page 84 for example under "Crash & Damage Rules":
Damage is based on relative speed.
When something hits a stationary object then the only thing to worry about is the speed of the moving object.
Then an example is given:
Mike is traveling at 40mph,
a motorcycle approaches from the opposite direction at 60mph.
Their added speeds are 100mph
so the damage to both vehicles is 10D8
So your assumption is disproven.
Blue_Lion wrote:Seams quite clear it is stating it is the speed the target is traveling at determines the level of the penalty.
"running" is just a hypothetical example in the case of a mundane runner and an unmoving attacker.
It doesn't mean it applies in all cases of runners, since there are runners faster than 20mph (Hyperion Juicers, Borgs) and higher speeds even for mundanes if you are traveling away from them.
Blue_Lion wrote:As written it does not indicate in any way it using speed relative to the attacker. So as written it would be using the commonly used method to determine how fast something is traveling.(The same method that is used by police to determine if you are driving faster than the speed limit.)
Speed limits do not have attackers, they are measuring how fast you're moving along a road.
Blue_Lion wrote:So if vehicle A is traveling at 70 MPH and vehicle B is traveling at traveling at 70 MPH.
If vehicles A and B shoot at a tree on the side of the road how fast is the tree traveling? (It is not but the speed relative to the attacker is 70 mph.)
Are you thinking it would be easier to fire at a rooted tree you're flying past at Mach 1 than someone you're holding hands with flying beside you at Mach 1?
If vehicle A shoots at vehicle B at what speed is vehicle B traveling at? (70 MPH speed relative to the attacker is unknown.)
Blue_Lion wrote:If Bob and Sue are sitting in vehicle A how fast are they traveling? (70 MPH even though speed relative to each other is 0.)
There isn't a single answer here.
In respect to calculating how long it takes them to get to their destination, 70
In respect to how long it takes them to get to each other, 0
Blue_Lion wrote:Does Bob stop traveling because Sue shoots him for copping a feel?
If you're sitting side by side, you aren't "traveling" any closer or further away from each other, even if you are in a moving vehicle.
If you fly in a plane from US to UK you are only traveling in respect to New York and London, not your seatmate.
If your seatmate wants to slap you, where either of you are in respect to NY and London does not matter.
Blue_Lion wrote:Honestly the two people in the same vehcile is not related to the orginal point, just an attempt to try and create a specail case to make the use of the rule seam illogical.
This is not a "special case", it's an example to show how your reasoning falls apart, which is better understood at high velocities.
Blue_Lion wrote:The oginial point was using the difrence of the speed of a missile and your vechile is a house rule. Casing a missile with a jet does not matter to the rule as written.
Your assumption that the Earth exists as and much be used as the frame of reference is your house rule.
That an attacker will always exist as a frame of reference by which to measure a target's speed is FACT.