Physics Question in hurr

[rb26deet32]

It's been over 10 years since I took physics and I lack some of the terminology that I once had. But I'm wanting someone who remembers physics to explain this one to me.

 

If a train is at rest and I run 20mph in its direction and jump into a train vs a train going 20mph and hitting me as I jump.

 

 

From what I remember there is more damage done when the train is going 20mph than when I am running 20mph because the train has a lot higher mass and momentum along with all of the kinetic energy. But I'm trying to figure out how much more damage there will be when it's the train moving and not me running.

 

If that makes sense cool. If not, I'll go and find a physics book because I'm having a huge brain fart right now.

[zeitgeist57]

kinetic energy?

 

mass X velocity...

[rb26deet32]

kinetic energy?

 

mass X velocity...

 

No, I have that one. I'm trying to figure out the difference in damage in either scenario. I might just be over thinking it...

 

The train moving 20mph has a ridiculously high amount of kinetic energy compared to a person running 20mph. But in a collision is there a difference in the damage caused to the person/train? That's my main question I guess. Running into a wall at 20mph or a wall hitting you at 20mph.

 

I miss knowing stuff...

[cybe]

http://www.engineeringtoolbox.com/impact-force-d_1780.html

[rb26deet32]

http://www.engineeringtoolbox.com/impact-force-d_1780.html

 

That's exactly what I was looking for.

 

All I could find when searching was random car/train crash videos.

 

Thanks

[Draco-REX]

I'm pretty sure the total damage should be the same. The only difference is that instead of going from 20 to 0 in an instant, you're going from 0 to 20 in an instant. The same amount of energy is used/given up. While the train does have massively more energy than you, it's only going to lose as much needed to accelerate your body to a velocity that the total mass (train + you) would travel at with the available energy.

 

This is all just at the moment of impact between two like bodies of disparate mass. After impact you get into materials. You running into the stationary train, you'll bounce off mostly. The train hitting you, you're likely going for a ride which may do more damage due to your construction.

[rb26deet32]

I'm pretty sure the total damage should be the same. The only difference is that instead of going from 20 to 0 in an instant, you're going from 0 to 20 in an instant. The same amount of energy is used/given up. While the train does have massively more energy than you, it's only going to lose as much needed to accelerate your body to a velocity that the total mass (train + you) would travel at with the available energy.

 

This is all just at the moment of impact between two like bodies of disparate mass. After impact you get into materials. You running into the stationary train, you'll bounce off mostly. The train hitting you, you're likely going for a ride which may do more damage due to your construction.

 

That's essentially what I've been thinking. But if you only consider the damage done at impact (meaning not getting run over afterwards) they should be pretty similar. It came up from watching a football game where they called a targeting call when the db used his shoulder to hit a receiver. And some how we got onto the topic of hitting a train...

 

Beer does crazy things lol.