relativity

Sam the Bam said:

A bicyclist is climbing a steep hill, 5 mph. Another
is heading down, 30 mph. Same size, same bikes.
They collide.

Who gets hurt worse?

Sam

see Newton's third law.

Sam who? said:

A bicyclist is climbing a steep hill, 5 mph. Another is heading
down, 30 mph. Same size, same bikes. They collide.

Quoted message said:

Who gets hurt worse?

Center of mass calculations. Obviously the guy going fast is worse
off. I notice that when a train hits a standing car. It destroys the
train... doesn't it?

Practically speaking, the fast rider is worse off because it isn't a
mirror image collision so there is some sort of glancing blow. After
colliding both riders may be equally injured but the fast guy still
has a hard collision with the ground or other obstacle coming before
he stops.

Jobst Brandt

"Sam the Bam" <[email hidden]> wrote in message news:
[email hidden]...

Quoted message said:

A bicyclist is climbing a steep hill, 5 mph. Another
is heading down, 30 mph. Same size, same bikes.
They collide.

Who gets hurt worse?

Sam

All you need is the Law of Conservation of Linear Momentum.

You didn't specify how steep the hill is, but that is not important in
this regard. We can simply ignore that, and assume it is level.

The momentum in the 5mph cyclist is (Mass x 5), while the momentum is
the 30mph cyclist is (-Mass x 30). After they collide, the total
momentum is (-Mass x 25). The combined twisted wreck will be
travelling at a speed of (-Mass x 25)/(2 x Mass)=(-12.5 mph).

That is, after they have collided, the combined twisted wreck will be
travelling at 12.5 mph in the downhill direction. Since the downhill
cyclist suffers a reduction in speed of 17.5 mph, and the uphill
cyclist suffers a change in speed of (5+12.5=17.5)mph, both of them
have a change in speed of 17.5mph. And because Force is proportional
to dV/dt, they both will experience the same traumatic force due to
the collision.

Do you agree?

Wannabe
=======

On Mon, 04 Jun 2007 20:10:08 -0000, [email hidden]

Quoted message said:

"Sam the Bam" <[email hidden]> wrote in message news:
[email hidden]...

Quoted message said:

A bicyclist is climbing a steep hill, 5 mph. Another
is heading down, 30 mph. Same size, same bikes.
They collide.

Who gets hurt worse?

Sam

All you need is the Law of Conservation of Linear Momentum.

You didn't specify how steep the hill is, but that is not important in
this regard. We can simply ignore that, and assume it is level.

The momentum in the 5mph cyclist is (Mass x 5), while the momentum is
the 30mph cyclist is (-Mass x 30). After they collide, the total
momentum is (-Mass x 25). The combined twisted wreck will be
travelling at a speed of (-Mass x 25)/(2 x Mass)=(-12.5 mph).

That is, after they have collided, the combined twisted wreck will be
travelling at 12.5 mph in the downhill direction. Since the downhill
cyclist suffers a reduction in speed of 17.5 mph, and the uphill
cyclist suffers a change in speed of (5+12.5=17.5)mph, both of them
have a change in speed of 17.5mph. And because Force is proportional
to dV/dt, they both will experience the same traumatic force due to
the collision.

showoff

Quoted message said:

Do you agree?

Wannabe
=======

Quoted message said:

That is, after they have collided, the combined twisted wreck will be
travelling at 12.5 mph in the downhill direction
Since the downhill
cyclist suffers a reduction in speed of 17.5 mph, and the uphill
cyclist suffers a change in speed of (5+12.5=17.5)mph, both of them
have a change in speed of 17.5mph. And because Force is proportional
to dV/dt, they both will experience the same traumatic force due to
the collision.

Do you agree?

Wannabe
=======

No. The guy going uphill gets way more whiplash.

Trav

Sam the Bam said:

A bicyclist is climbing a steep hill, 5 mph. Another
is heading down, 30 mph. Same size, same bikes.
They collide.

Who gets hurt worse?

Sam

Seems like the guy going faster has more momentum. So after the crash
and the two guys are both lying on the ground in pain, the fast guy is
probably going to take a lot longer to get up. But I wouldn't want to be
either one of them.

Ken

Sam the Bam said:

A bicyclist is climbing a steep hill, 5 mph. Another
is heading down, 30 mph. Same size, same bikes.
They collide.

Who gets hurt worse?

Sam

I think the guy going faster gets hurt more.
Is this a trick question?

Sam the Bam said:

A bicyclist is climbing a steep hill, 5 mph. Another
is heading down, 30 mph. Same size, same bikes.
They collide.

Who gets hurt worse?

"Hey, you got chocolate in my peanut butter!"

Quoted message said:

Sam who? said:

A bicyclist is climbing a steep hill, 5 mph. Another is heading
down, 30 mph. Same size, same bikes. They collide.

Quoted message said:

Who gets hurt worse?

Center of mass calculations. Obviously the guy going fast is worse
off. I notice that when a train hits a standing car. It destroys the
train... doesn't it?

No.

When I was training to drive trucks, we received a lecture from the
local train company. Lots of nice video of trains hitting all manner
of vehicles. Regardless of the vehicle, it was train 1 vehicle 0.
The only exception would be if the vehicle managed to derail the train,
in which case it's a tie (takes a lot of luck to derail a train).

It's not just about energy. Who hits what where also matters.

I don't want to be in that collision, regardless of which rider I am.

Quoted message said:

Who gets hurt worse?

Sam

The guy with the better lawyer.

-Mike K.

Sam the Bam said:

A bicyclist is climbing a steep hill, 5 mph. Another
is heading down, 30 mph. Same size, same bikes.
They collide.

Who gets hurt worse?

Sam

The center of mass for the descending rider will be higher, as its "up
the slope".
The translational component of the collision is not the only part to
figure in here, as there will be a rotational component also ...
meaning that some momentum will be translated into the descending
rider going endo. If you're attempting a tackle in NFL-style football,
undercutting a 260 lb tight end isn't the worst way to go ...

As these are non-point sources (geometrically complex objects) you're
going to need to state more assumptions before I'll go any further.

Perhaps a set of models on an inclined plane would be a good place to
test ... or send the request off to MythBusters.

-bdbafh

Mike said:

Quoted message said:

Who gets hurt worse?

Quoted message said:

Sam

The guy with the better lawyer.

Wonderful :-D

Mike said:

Quoted message said:

Who gets hurt worse?

Sam

The guy with the better lawyer.

-Mike K.

Or vice versa.

On Tue, 05 Jun 2007 01:41:35 GMT, R Brickston

rb20170REMOVE.yahoo.com@ said:

Mike said:

Quoted message said:

Who gets hurt worse?

Sam

The guy with the better lawyer.

-Mike K.

Or vice versa.

Actually meant: The guy with the worse lawyer.

Sam the Bam said:

A bicyclist is climbing a steep hill, 5 mph. Another
is heading down, 30 mph. Same size, same bikes.
They collide.

Who gets hurt worse?

Both experience the same amount of energy from the impact.

Peace favor your sword (IH),
Kirk

FREE historic Western Martial Arts manuals:
http://www.lulu.com/lawson

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"My shoes are too tight, but it doesn't matter, because I have forgotten how to dance."

"...it's the nature of the media and the participants. A herd of martial artists gets together and a fight breaks out; quelle surprise."
-Chas Speaking of rec.martial-arts

Quoted message said:

Sam who? said:

A bicyclist is climbing a steep hill, 5 mph. Another is heading
down, 30 mph. Same size, same bikes. They collide.

Quoted message said:

Who gets hurt worse?

Center of mass calculations. Obviously the guy going fast is worse
off. I notice that when a train hits a standing car. It destroys the
train... doesn't it?

In this case the train and car have equal mass. Recite Newton's
third law. And remember the motion is relative.

Quoted message said:

"Sam the Bam" <[email hidden]> wrote in message news:
[email hidden]...

Quoted message said:

A bicyclist is climbing a steep hill, 5 mph. Another
is heading down, 30 mph. Same size, same bikes.
They collide.

Who gets hurt worse?

Sam

All you need is the Law of Conservation of Linear Momentum.

And remember that momentum is observer dependent... So momentum
from each observer's point of view is identical.

Just A User said:

Sam the Bam said:

A bicyclist is climbing a steep hill, 5 mph. Another
is heading down, 30 mph. Same size, same bikes.
They collide.

Who gets hurt worse?

Sam

Seems like the guy going faster has more momentum. So after the crash
and the two guys are both lying on the ground in pain, the fast guy is
probably going to take a lot longer to get up. But I wouldn't want to be
either one of them.

Ken

Momentum is relative. The momentum from each observer's point of view
is identical.

Quoted message said:

Sam the Bam said:

A bicyclist is climbing a steep hill, 5 mph. Another
is heading down, 30 mph. Same size, same bikes.
They collide.

Who gets hurt worse?

Sam

I think the guy going faster gets hurt more.
Is this a trick question?

Physics typically requires calculation. The trick is to do the
calculations.