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 Wulfmar wrote:
It's never possible to go faster than terminal velocity!

It is, but you need some means of acceleration. Overcoming the pull of gravity and air resistance is how flight is made possible, after all. Supersonic jets, for example, are moving much faster than terminal velocity.

For the scenario provided here, I am assuming that the Marine in question is falling into an Earth-like planet. If not, if it is some low-gravity world or something like that, then it's exceedingly possible for the Marine to survive the drop... in fact, if the planet is low-G enough, it might actually be impossible for the Marine to even get pulled into its gravity well.

Terminal Velocity

= Maximum Velocity.

If you change one force, you simply move the maximum velocity for the given factors.

Terminal is terminal, it will change according to the variables present, but it will ALWAYS be terminal.


Question = if you add a jetpack as you say and boost the rate of falling to the maximum the jetpack can push you - what is the new maximum speed called?

 Wulfmar wrote:
No, it is NOT. EVER.

Yes it is. If you stand on top of a building and fire a .30cal gun with a muzzle velocity of 700m/s straight at the ground, will the bullet hit the ground at 90m/s (the terminal velocity of a .30cal bullet in free fall) or slightly less than 700m/s?

Okay you know what, don't listen to the teacher.

 Wulfmar wrote:
Terminal Velocity

= Maximum Velocity.

If you change one force, you simply move the maximum velocity for the given factors.

Terminal is terminal, it will change according to the variables present, but it will ALWAYS be terminal.


Question = if you add a jetpack as you say and boost the rate of falling to the maximum the jetpack can push you - what is the new maximum speed called?

You are assuming an initial velocity of zero. If an object is thrown down (which is effectively what has happened in the space marine scenario as he is entering the atmosphere with a non-zero initial velocity), rather than dropped, it can exceed the terminal velocity. It just means that it will decelerate towards that terminal velocity rather than accelerate towards it.

If the time of flight is not long enough for the object to decelerate to its terminal velocity, then it will impact at a higher velocity.


Automatically Appended Next Post:

 Wulfmar wrote:
Okay you know what, don't listen to the teacher.

I do listen to teachers.

My Professors.

Nope, still not making sense.


You're assuming as is taught at secondary school that Terminal Velocity is ONLY relevant to moving through air.

This is not true. It's the movement through any medium.


Before anyone says it, Space is NOT a true vacuum either. There will be friction.

 A Town Called Malus wrote:

I do listen to teachers.

My Professors.

What kind of professors have got that so horrendously wrong? You should demand your money back from the course (or, as I'm assuming, you haven't paid attention to them properly because NO professor would make that daft assertion that you can go faster than your MAXIMUM/TERMINAL velocity. You can CHANGE the terminal velocity, but you will never exceed it.)

 Wulfmar wrote:
Terminal Velocity

= Maximum Velocity.

If you change one force, you simply move the maximum velocity for the given factors.

Terminal is terminal, it will change according to the variables present, but it will ALWAYS be terminal.


Question = if you add a jetpack as you say and boost the rate of falling to the maximum the jetpack can push you - what is the new maximum speed called?

If the pull of gravity coupled with the resistance of the atmosphere is expressed as X, we reach a terminal velocity of X, where the falling object's total acceleration is 0 (Pull of gravity vs air resistance must = 0 to reach terminal velocity). If the jet-pack adds a maximum acceleration of 150m/s, the Velocity of the Object is now X+150m/s.

So, in our fictional planet here, if terminal velocity (X) is 120m/s, adding the jetpack means the Marine is now flying at 270m/s straight down. He is now falling faster than the planet could possibly pull him down unaided.

https://en.wikipedia.org/wiki/Terminal_velocity

 Psienesis wrote:

 Wulfmar wrote:
Terminal Velocity

= Maximum Velocity.

If you change one force, you simply move the maximum velocity for the given factors.

Terminal is terminal, it will change according to the variables present, but it will ALWAYS be terminal.


Question = if you add a jetpack as you say and boost the rate of falling to the maximum the jetpack can push you - what is the new maximum speed called?

If the pull of gravity coupled with the resistance of the atmosphere is expressed as X, we reach a terminal velocity of X, where the falling object's total acceleration is 0 (Pull of gravity vs air resistance must = 0 to reach terminal velocity). If the jet-pack adds a maximum acceleration of 150m/s, the Velocity of the Object is now X+150m/s.

And what would you call this new maximum speed?

 Wulfmar wrote:
Nope, still not making sense.


You're assuming as is taught at secondary school that Terminal Velocity is ONLY relevant to moving through air.

This is not true. It's the movement through any medium.


Before anyone says it, Space is NOT a true vacuum either. There will be friction.

The density of space is approximately 1 atom per cubic centimetre. And that is one of the higher estimates. So, yes, a 1cm box moving at 1m/s will bump into a single atom every second. Which will have no measurable effect on the velocity of the box.

 A Town Called Malus wrote:

I do listen to teachers.

My Professors.

What kind of professors have got that so horrendously wrong? You should demand your money back from the course (or, as I'm assuming, you haven't paid attention to them properly because NO professor would make that daft assertion that you can go faster than your MAXIMUM/TERMINAL velocity. You can CHANGE the terminal velocity, but you will never exceed it.)

Your interpretation is wrong because it cannot satisfy real world observations.

For example, could you answer the gun question? Because your interpretation leads to the answer that as soon as the force on the bullet is gone, it will instantaneously start travelling at its terminal velocity of 90m/s.

Alternatively, the terminal velocity of a tennis ball is 60 mph. The fastest recorded tennis serve is 163.7mph. According to you, that is impossible.

So, you are wrong. The terminal velocity of an object can be exceeded provided that the initial force is big enough or the object is entering a medium with a higher density than the one it is leaving and it has a speed greater than the terminal velocity for the denser medium.

 Wulfmar wrote:

 Psienesis wrote:

 Wulfmar wrote:
Terminal Velocity

= Maximum Velocity.

If you change one force, you simply move the maximum velocity for the given factors.

Terminal is terminal, it will change according to the variables present, but it will ALWAYS be terminal.


Question = if you add a jetpack as you say and boost the rate of falling to the maximum the jetpack can push you - what is the new maximum speed called?

If the pull of gravity coupled with the resistance of the atmosphere is expressed as X, we reach a terminal velocity of X, where the falling object's total acceleration is 0 (Pull of gravity vs air resistance must = 0 to reach terminal velocity). If the jet-pack adds a maximum acceleration of 150m/s, the Velocity of the Object is now X+150m/s.

And what would you call this new maximum speed?

Flight.

Are you guys really arguing over terminology ?

+ Going to leave this here :

https://www.grc.nasa.gov/www/k-12/airplane/termv.html

 Wulfmar wrote:


And what would you call this new maximum speed?

You would not call it the terminal velocity as that is a well defined parameter.

It would be akin to describing the electrostatic force as gravity because it attracts stuff.

The terminal velocity of an object is the speed at which the force due to gravity and the force due to air resistance are equal in magnitude. It is not the absolute maximum velocity that an object can travel at. Only the speed of light has that honour.

Man jumps out a plane with a gun.
Man falls due to gravity. Air resistance (drag) increases until Terminal Velocity is reached.
Man fires gun downwards - bullet travels out with a higher Terminal Velocity due to the force of the shot
Air resistance will act upon it in exactly the same way. Eventually downwards force (gravity and thrust) will equal out to reach a new Terminal Velocity. During this process, Terminal Velocity will decrease to a new set point.



Did you guys ever get taught about the guy jumping from an aeroplane and opening a parachute and how his terminal velocity changes? Absolutely NO difference here.

Same with an object entering the atmosphere - Terminal Velocity in space changes when friction increases due to entering the atmosphere.

Rubbish?

"Terminal velocity is the highest velocity attainable by an object as it falls through air"

Tell me, is a bullet fired from a gun straight downwards "falling"? Because it's moving considerably faster than it would be if you just dropped it.

 Flinty wrote:
Re the swimming question... It's power armour. They probably just need to set it to a repetitive thrash with the legs and leave the thing to it.

They also can use the exhausts in the backpack for jet propulsion. They use it in space, no reason why they can't set the fusion reactor to overdrive to "fly" through the water.

 Wulfmar wrote:
I actually can't believe the rubbish I'm reading on here tonight.


Man jumps out a plane with a gun.
Man falls due to gravity. Air resistance (drag) increases until Terminal Velocity is reached.
Man fires gun downwards - bullet travels out with a higher Terminal Velocity due to the force of the shot
Air resistance will act upon it in exactly the same way. Eventually downwards force (gravity and thrust) will equal out to reach a new Terminal Velocity. During this process, Terminal Velocity will decrease to a new set point.



Did you guys ever get taught about the guy jumping from an aeroplane and opening a parachute and how his terminal velocity changes? Absolutely NO difference here.

Same with an object entering the atmosphere - Terminal Velocity in space changes when friction increases due to entering the atmosphere.

Terminal velocity is a fixed value for given mass, acceleration due to gravity, density of medium, drag coefficient and area. It is calculated by setting the force of gravity equal to the force of air resistance and solving for velocity. It is not just the velocity that the object happens to be travelling at at any moment in time.

If an object is at terminal velocity in a low density medium and enters a denser medium then the force due to drag will increase. This increase in drag will slow the object down over time until such a point as the forces are balanced again. It is only when the forces of air resistance and gravity are balanced that an object is travelling at its terminal velocity. For all the time at which those forces are not balanced, the object has been falling faster than its terminal velocity.

WAIT: I see what has happened

English is a donkeycave of a language (I'm not English though I've moved here). Maximum does not equal Terminal. Am I right?

That's why I was writing Maximum/Terminal in previous posts.

Terminal would be more like "Final", I guess. But I'm not a native English speaker.

Okay then, let's get back to the question instead of your e-peen contest trying to convince the other (who has a set opinion roughly as likely to change as a set and hardened concrete sidewalk is when I slap it with my hand) you're right about terminal velocity.

TLDR: Both of you stop wasting other's time and go to pm if you want to keep bickering.

Terminal velocity is a defined term, and in no way means maximum velocity except in a very specific set of circumstances (that is, free-fall in a sufficiently dense atmosphere).

 Unit1126PLL wrote:
Terminal velocity is a defined term, and in no way means maximum velocity except in a very specific set of circumstances (that is, free-fall in a sufficiently dense atmosphere).

 LethalShade wrote:
Terminal would be more like "Final", I guess. But I'm not a native English speaker.

Thanks - didn't realise they meant different things. They're right

 Wulfmar wrote:

 Unit1126PLL wrote:
Terminal velocity is a defined term, and in no way means maximum velocity except in a very specific set of circumstances (that is, free-fall in a sufficiently dense atmosphere).

 LethalShade wrote:
Terminal would be more like "Final", I guess. But I'm not a native English speaker.

Thanks - didn't realise they meant different things. They're right

No problem. I always like a bit of physics debate in my wargaming

The penny dropped when I looked at the link and translated it and it came up with a different word: Endgeschwindigkeit and not maximal - I was starting to think the world gone mad xD

 Psienesis wrote:


For the scenario provided here, I am assuming that the Marine in question is falling into an Earth-like planet. If not, if it is some low-gravity world or something like that, then it's exceedingly possible for the Marine to survive the drop... in fact, if the planet is low-G enough, it might actually be impossible for the Marine to even get pulled into its gravity well.

Problem I see is OP makes mention of a Necron being the subject, but then posits the question as if the subject was in fact a Space Marine.

If they did then the idea of transporting them via drop pods and Thunderhawk would be made moot. Even meteorites don't survive re-entry intact.

The case with Vesna Vulovic is a bit misleading: she survived a free fall but she was inside the plane when it crashed, which presents very different circumstances as oppose to falling out of a plane to the ground.

In all cases involving humans surviving free falls, none of them walked away unscathed, and certainly not in condition to start making a fight within minutes. It can take months if not years for people to recover.

A Space Marine might be expected to survive free fall (assuming things like Earth-level gravity and hospital environment, etc.) provided he is recovered by Apothecaries and treated accordingly.
I suppose you can just make it so a Space Marine crashes to a planet and just gest up to swing his chainsword, but that makes for a less interesting story.

if I were the OP I'd just adjust the story where planetary characteristics (like gravity fluctations, or falls into an ocean of soft mud), or equipment the character has on hand, allowed for survival. Otherwise it wouldn't make for an interesting or compelling story when impractical scenarios have the characters walking away unscathed. Not unless you want the story made into a Micheal Bay movie!

flirice wrote:

 Psienesis wrote:


For the scenario provided here, I am assuming that the Marine in question is falling into an Earth-like planet. If not, if it is some low-gravity world or something like that, then it's exceedingly possible for the Marine to survive the drop... in fact, if the planet is low-G enough, it might actually be impossible for the Marine to even get pulled into its gravity well.

Problem I see is OP makes mention of a Necron being the subject, but then posits the question as if the subject was in fact a Space Marine.

If they did then the idea of transporting them via drop pods and Thunderhawk would be made moot. Even meteorites don't survive re-entry intact.

The case with Vesna Vulovic is a bit misleading: she survived a free fall but she was inside the plane when it crashed, which presents very different circumstances as oppose to falling out of a plane to the ground.

In all cases involving humans surviving free falls, none of them walked away unscathed, and certainly not in condition to start making a fight within minutes. It can take months if not years for people to recover.

A Space Marine might be expected to survive free fall (assuming things like Earth-level gravity and hospital environment, etc.) provided he is recovered by Apothecaries and treated accordingly.
I suppose you can just make it so a Space Marine crashes to a planet and just gest up to swing his chainsword, but that makes for a less interesting story.

if I were the OP I'd just adjust the story where planetary characteristics (like gravity fluctations, or falls into an ocean of soft mud), or equipment the character has on hand, allowed for survival. Otherwise it wouldn't make for an interesting or compelling story when impractical scenarios have the characters walking away unscathed. Not unless you want the story made into a Micheal Bay movie!

Indeed its going to depend on the landing by a Space amrine has much better healing abilities and redundancies than a human - he is likely to be several damaged by=ut might be able to operate in some form:

Also another interesting free fall that only resulted in minor injuries: (but he hit trees and snow)

n the night of 24 March 1944, 21-year-old Alkemade was one of seven crew members in Avro Lancaster B Mk. II, DS664,[1] of No. 115 Squadron RAF. Returning from a 300 bomber raid on Berlin, east of Schmallenberg, DS664 was attacked by a Luftwaffe Ju 88 night-fighter, flown by Hauptmann Gerhard Friedrich, 1./NJG 6 , caught fire and began to spiral out of control. Because his parachute was unserviceable, Alkemade jumped from the aircraft without one, preferring to die by impact rather than burn to death. He fell 18,000 feet (5,500 m) to the ground below.
His fall was broken by pine trees and a soft snow cover on the ground. He was able to move his arms and legs and suffered only a sprained leg

Re-entry and free-fall are way different.

For example, a log can survive free-fall from, say, 10,000 feet, likely with only some cracks and splinters. But it cannot survive re-entry, I guarantee it would incinerate into ash and particles before it came anywhere near 10,000 feet, even.

Terminal velocity only applies to freefall. Terminal velocity is tje macimum velocity an object can fall at. If you use a jetpack or apply additional forces its no longer falling, its being push/flown/whatever.

As for surviving r-entry, I reckon it could be done if the Marine has sufficient plot armour/bad ass points/strength of will to not die. Space Marine armour is capable of withstanding heavy flamers which can melt through the heavy steel that makes up Ork Heavy Armour, so that's around about 2700 celsius. Dunno how hot Flamestorm cannons are but probably significantly more. The armour would likely be cracked, melted and useless, but the marine might survive. If he was in good condition before falling and had his fall sloeed sufficiently, or hit a mountain at the right angle to roll down, as in parrallel, he could survive. And before someone says that's rubbish, that's the same advice I got when friends of mine did skydiving. Aim for trees, bushes or roll down a hill.


As for underwater, the third lung is capable of breathing in water. The biggest danger would be pressure. Astartes can most certainly take much higher pressure than humans even unarmoured. Maybe not 4 miles deep pressure, maybe 2-3 times what humans can handle. Armoured they can probably survive any pressure. The only issues then are the slower movements (negligible) and getting anywhere, but they have Land Raiders to get them places.


Automatically Appended Next Post:
Plus, Vulkan wasn't wearing his armour when he did reentry, which is why he burnt up.

Steel melts at ~1500 degrees celsius, not 2700.

The Apollo command modules reached ~2700 degrees celsius on re-entry.

Question is, would the power armour of a space marine boil away on re-entry (and so act as an ablative heat shield like the heat shields of the command module and space shuttle) or would it just get hotter and hotter, in which case we're going to end up with a very cooked marine?

 A Town Called Malus wrote:
Steel melts at ~1500 degrees celsius, not 2700.

The Apollo command modules reached ~2700 degrees celsius on re-entry.

Question is, would the power armour of a space marine boil away on re-entry (and so act as an ablative heat shield like the heat shields of the command module and space shuttle) or would it just get hotter and hotter, in which case we're going to end up with a very cooked marine?

Pardon me, I was thinking in Farenheit from watching US blacksmiths.

I am tempted to think that the latter. See, they have a ceramite layer which is heat resistant. Ceramite is the stuff that protects Stormravens and other flyers from re-entry and melta weapons and it doesn't peel off.

Ceramite is notoriously heat-resistant. I am pretty sure he'd survive the re-entry if the armour is intact.

As for the ground impact, it depends on how he lands. On his neck? He's dead. On his feet? A Marine has survived falling through an elevator shaft in the kilometres before. He'll break his legs, but it's merely a setback.