Enhanced Move, Slams, and Explosions

[johndallman]

Originally Posted by ErhnamDJ

And I'm not really sure what reasoning there is for why it's different with my speedster here. It feels wrong, but I don't know much about physics.

Superheroic mega-speedsters are clearly not physics compliant. If she starts out at a gentle stroll, only a million miles per hour, there are several difficult problems if you let physics into the room at all. Here are some samples:

1. She needs to explain where she gets the energy for this motion. "Food" is not the answer: burning tissue paper does not build a hydrogen bomb.
2. She obviously isn't propelled by her legs, since the forces she'd have to exert would reduce concrete to sand, depriving her of traction.
3. The heat and shockwaves as she moves through the air demolish everything and kill everyone for miles around.
4. Without some huge force holding her down, she leaves the earth's surface and heads off into space, going faster than any rocket mankind has ever launched. Earth's gravity is completely inadequate to hold her down.
5. With all those problems solved, how does she avoid running into things within a few milliseconds? With only ATR 1, her reflexes are completely inadequate for seeing things and going round them.

So don't appeal to physics. It will just laugh at you.

[ErhnamDJ]

Originally Posted by johndallman

[*]With all those problems solved, how does she avoid running into things within a few milliseconds? With only ATR 1, her reflexes are completely inadequate for seeing things and going round them. [/LIST]

Well, she has Enhanced Time Sense, which doesn't go into much detail at all.

As for the rest of it, we're handwaving all that away and saying it's covered by Enhanced Move (Ground). It says what it does.

So don't appeal to physics. It will just laugh at you.

So what would you have happen when she hits something while moving at these insane speeds?

[DouglasCole]

Originally Posted by ErhnamDJ

So what would you have happen when she hits something while moving at these insane speeds?

Well, the kinetic energy of a 50kg object at 500,000m/s (about a million miles per hour) is 6.25 x 10^12 joules. That's about a kiloton of energy, in atomic bomb terms.

So, when she hits something, esp something solid (of course, at that speed, AIR is probably solid), she explodes with about 1kT of energy.

[Refplace]

Originally Posted by johndallman

Superheroic mega-speedsters are clearly not physics compliant.
So don't appeal to physics. It will just laugh at you.

This. Cant have your cake and eat it to (always thought that was an odd expression). If your ignoring physics which this character definitely is then you cant call on it to help you either.

Anyhow back to the case at hand.
I would cap the damage based on the lower of the two objects HP.
So your character hits and instead of a massive explosion you have a nice fine mist. What are the HP and DR anyhow?
Also you do have Second Nature or the Supers version on that Enhanced Move right? Otherwise aiming and getting quickly up to speed will be an issue.

[Refplace]

Originally Posted by DouglasCole

Well, the kinetic energy of a 50kg object at 500,000m/s (about a million miles per hour) is 6.25 x 10^12 joules. That's about a kiloton of energy, in atomic bomb terms.

So, when she hits something, esp something solid (of course, at that speed, AIR is probably solid), she explodes with about 1kT of energy.

I was hoping one of you math heavy types would chime in. I would have to research those numbers :)
What about the idea of a damage cap based on DR and HP? Since thats covering mass in GURPS terms.

[ErhnamDJ]

Originally Posted by DouglasCole

of course, at that speed, AIR is probably solid

We have, perhaps unwisely, decided that air resistance isn't a problem with Enhanced Move. Not that it would have been a big deal to purchase Insubstantiality with some limitations for that. It was just that none of the other writeups I've seen have ever dealt with air.

[ErhnamDJ]

Originally Posted by Refplace

Anyhow back to the case at hand.
I would cap the damage based on the lower of the two objects HP.
So your character hits and instead of a massive explosion you have a nice fine mist.

But at that speed? It just doesn't seem right to me. I wouldn't put up any fight if that was the ruling. At least then I wouldn't have to worry about tripping on a rock and accidentally blowing up a city, so it would seem like an okay tradeoff. But it still doesn't feel right to me.

What are the HP and DR anyhow?

She has HP 10 and no DR but 2 on her feet.

Also you do have Second Nature or the Supers version on that Enhanced Move right? Otherwise aiming and getting quickly up to speed will be an issue.

She has Instantaneous Acceleration and Complete Maneuverability. I made her before Power-Ups 4 was out, or I might have got her the full Second Nature package. But hers is a burst ability. It's not on all the time, so I probably wouldn't have.

[johndallman]

Originally Posted by ErhnamDJ

Is that always true? What's the fastest thing humans have ever put into space? Does that not explode if it hits something?

Low-speed collisions just smash things and any explosion is due to explosive materials. Part of the energy released in any collision is converted to heat, and if there's enough of it, that converts some of the material involved to gas, or plasma if hot enough, and that explodes. This effect is not significant for vehicles within earth's atmosphere.

Your speedster, however, is a different matter. She's making about 1.667E6 metres/sec, and if she's medium-sized at 50kg, her kinetic energy is about 6.9E13 joules, about 17 kilotons of TNT equivalent, if I have my sums right. Not all of that will go into an explosion, but there would be a significant bang if the following applied:

1. She's moving at this speed, which is impractical within Earth's atmosphere.
2. Whatever means she uses to avoid collisions normally doesn't prevent it.
3. Whatever she hits is solid enough to stop her - you'd need something very large and well-anchored.

[DouglasCole]

Originally Posted by Refplace

I was hoping one of you math heavy types would chime in. I would have to research those numbers :)
What about the idea of a damage cap based on DR and HP? Since thats covering mass in GURPS terms.

My number is basically the 1/2 M V^2 energy of the runner, and roughly 4 trillion joules per kiloton.

[ErhnamDJ]

Originally Posted by DouglasCole

So, when she hits something, esp something solid (of course, at that speed, AIR is probably solid), she explodes with about 1kT of energy.

Also, how much damage is 1kT?

Her slam damage is 62,914d+188,742. On an AoA (Strong), anyway.

And I was wondering how her slam damage might relate to the damage she does on an explosion.