Things I learned by being stupid today

[Joe]

I know seat belts help, but let me put some numbers behind what I said:

[tex]\Delta[/tex] speed: -60mph
Acceleration: between -30 and -60 miles per hour per second
Broken bones: Zero

[CrAz3D]

x86] link=topic=10599.msg135264#msg135264 date=1194411529]
I know seat belts help, but let me put some numbers behind what I said:

[tex]\Delta[/tex] speed: -60mph
Acceleration: between -30 and -60 miles per hour per second
Broken bones: Zero

Pictures?................................................

[Sidoh]

x86] link=topic=10599.msg135264#msg135264 date=1194411529]
[tex]\Delta[/tex] speed: -60mph

Impossible! :)

Speed is the magnitude of velocity, which clearly means that it is always [tex]\geq 0[/tex].

In case you're curious, it'd make more sense to say both [tex]\Delta v = -60[/tex] and [tex]1 \leq \Delta t \leq 2[/tex], which implies that the acceleration, [tex]-60 \leq a \leq -30[/tex] where [tex]a[/tex] is measured in mph/s (lol).

[Ender]

x86] link=topic=10599.msg135264#msg135264 date=1194411529]
I know seat belts help, but let me put some numbers behind what I said:

[tex]\Delta[/tex] speed: -60mph
Acceleration: between -30 and -60 miles per hour per second
Broken bones: Zero

As you said, you mowed down a bunch of trees. Thus your momentum changed slowly. Thus the force exerted on your car by the tree wasn't too bad. (Force is the derivative of momentum wrt time.)

This, however, is because you were lucky. If you hit a more resilient tree, it would be a completely different story. Your momentum would have gone from huge to zip in a split second, and bam, the tree would have hit your car hard.

Another way to think about this is if you were less lucky and hit a tougher tree, then your car would stop in a split second and your head would go flying into the wheel/surrounding instruments at 60mph.

So do you agree that you just got lucky? Or are you still skeptical?

[dark_drake]

x86] link=topic=10599.msg135264#msg135264 date=1194411529]
[tex]\Delta[/tex] speed: -60mph

Impossible! :)

Speed is the magnitude of velocity, which clearly means that it is always [tex]\geq 0[/tex].

[tex]\Delta[/tex]speed=speed₂-speed₁=0-60=-60

Speed might always be positive, but that doesn't mean the change in speed is. :P

[Sidoh]

[tex]\Delta[/tex]speed=speed₂-speed₁=0-60=-60

Speed might always be positive, but that doesn't mean the change in speed is. :P

lol, yeah.  I guess I saw speed with a negative and was too hasty to jump into a reply.  At least most of what I said (everything except the "impossible," I suppose :P) was correct, though. :)

[Camel]

I hit a tree at <5mph (I know this because the airbags are set to go off at 5mph and they didn't go off), and the car was totaled. Took the car in for a fix to the recalled power steering system, and the next day the car hurled its self in to a tree. Power steering fluid reservoir was empty. I called the dealership, and they accused me of drifting, which really pissed me off. I took a picture of the car and wrote down everything I could remember about all of the events relevant to the crash - conversations with the guys at the dealership etc. I have a pretty good case against them, and I'm going to the insurance board next Wednesday to make it.

x86] link=topic=10599.msg135264#msg135264 date=1194411529]
Acceleration: between -30 and -60 miles per hour per second

-60m/h/s = -27m/s/s
gravity (at sea level) = -9.8m/s/s

If it really took an entire second for you to slow to a stop, what you experienced was hardly a life threatening situation.

[iago]

-60m/h/s = -27m/s/s
gravity (at sea level) = -9.8m/s/s

If it really took an entire second for you to slow to a stop, what you experienced was hardly a life threatening situation.

You probably shouldn't equate velocity and acceleration like that, it looks wrong. And also, that's not technically "gravity", it's "acceleration due to gravity"

Also, if I'm understanding right, you're suggesting that the crumple zone of the car is 2m big? That seems a little much to me.

[Camel]

-60m/h/s = -27m/s/s
gravity (at sea level) = -9.8m/s/s

If it really took an entire second for you to slow to a stop, what you experienced was hardly a life threatening situation.

You probably shouldn't equate velocity and acceleration like that, it looks wrong. And also, that's not technically "gravity", it's "acceleration due to gravity"

Also, if I'm understanding right, you're suggesting that the crumple zone of the car is 2m big? That seems a little much to me.

I didn't mention velocity at all. I was insinuating that, according to the data he provided, he experienced less than 3Gs, which is nothing.

Are you high?

[Sidoh]

-60m/h/s = -27m/s/s
gravity (at sea level) = -9.8m/s/s

If it really took an entire second for you to slow to a stop, what you experienced was hardly a life threatening situation.

You probably shouldn't equate velocity and acceleration like that, it looks wrong. And also, that's not technically "gravity", it's "acceleration due to gravity"

Also, if I'm understanding right, you're suggesting that the crumple zone of the car is 2m big? That seems a little much to me.

He's equating acceleration to acceleration (m/h/s and m/s/s are both units of acceleration).  That's correct, but I'd say it's also nitpicking. :)

[iago]

-60m/h/s = -27m/s/s
gravity (at sea level) = -9.8m/s/s

If it really took an entire second for you to slow to a stop, what you experienced was hardly a life threatening situation.

You probably shouldn't equate velocity and acceleration like that, it looks wrong. And also, that's not technically "gravity", it's "acceleration due to gravity"

Also, if I'm understanding right, you're suggesting that the crumple zone of the car is 2m big? That seems a little much to me.

He's equating acceleration to acceleration (m/h/s and m/s/s are both units of acceleration).  That's correct, but I'd say it's also nitpicking. :)

Ah, I thought he was saying that 60 m/s had an acceleration of 30m/s/s.

But in that case, how can -60m/h/s = -27m/s/s? That makes even less sense, unless "m" is being used for two different units. No wonder I'm getting confused..

[Camel]

-60m/h/s = -27m/s/s
gravity (at sea level) = -9.8m/s/s

If it really took an entire second for you to slow to a stop, what you experienced was hardly a life threatening situation.

You probably shouldn't equate velocity and acceleration like that, it looks wrong. And also, that's not technically "gravity", it's "acceleration due to gravity"

Also, if I'm understanding right, you're suggesting that the crumple zone of the car is 2m big? That seems a little much to me.

He's equating acceleration to acceleration (m/h/s and m/s/s are both units of acceleration).  That's correct, but I'd say it's also nitpicking. :)

Ah, I thought he was saying that 60 m/s had an acceleration of 30m/s/s.

But in that case, how can -60m/h/s = -27m/s/s? That makes even less sense, unless "m" is being used for two different units. No wonder I'm getting confused..

Sorry, I didn't really read that before I posed; it should have read -60mph/s = -27m/s/s, sixty miles per hour per second equals twenty seven meters per second squared.

Proof.

[Sidoh]

Ah, I thought he was saying that 60 m/s had an acceleration of 30m/s/s.

But in that case, how can -60m/h/s = -27m/s/s? That makes even less sense, unless "m" is being used for two different units. No wonder I'm getting confused..

Yeah, it made me cringe a bit too, but I knew what he meant. :)

[Blaze]

So, are we getting pictures?

[Joe]

Like I told rabbit, my dad fixed most of the damage before the sun came back up.