Some Newtonian law states that "a body proceeding on a course, blah blah,
provided a force doesn't act on it, blah blah doesn't change and carries
on its own sweet way unmolested." I think that's how it goes anyway.

Now, as we all know, Force = Mass x Acceleration which implies that if I
get hit by something, no matter how heavy, provided it's not changing its
speed, I'll be fine. So if I cross the race track at the TT and in the
process get hit by some bike racer doing 190mph for example (which is not
at all unknown) I'll be totally unharmed. This seems kind of counter-
intuitive to me, at first sight, anyway, so.... where have I gone wrong
here?

Cursitor Doom wrote:

Now, as we all know, Force = Mass x Acceleration which implies that if I
get hit by something, no matter how heavy, provided it's not changing its
speed, I'll be fine.

It's the change in *your* speed (accelerating from near stationary to
near the bike's speed in a fraction of a second) that will hurt a bit.

Of course the bike will also decelerate as it hits you (conservation of
momentum).

On Saturday, 3 June 2017 22:51:05 UTC+1, Andy Burns wrote:
Cursitor Doom wrote:

Now, as we all know, Force = Mass x Acceleration which implies that if I
get hit by something, no matter how heavy, provided it's not changing its
speed, I'll be fine.

It's the change in *your* speed (accelerating from near stationary to
near the bike's speed in a fraction of a second) that will hurt a bit.

Of course the bike will also decelerate as it hits you (conservation of
momentum).

Since your change in speed is very rapid and your mass not zero, the force acting on you will be large and painful.


NT

Cursitor Doom was thinking very hard :
Some Newtonian law states that "a body proceeding on a course, blah blah,
provided a force doesn't act on it, blah blah doesn't change and carries
on its own sweet way unmolested." I think that's how it goes anyway.

Now, as we all know, Force = Mass x Acceleration which implies that if I
get hit by something, no matter how heavy, provided it's not changing its
speed, I'll be fine. So if I cross the race track at the TT and in the
process get hit by some bike racer doing 190mph for example (which is not
at all unknown) I'll be totally unharmed. This seems kind of counter-
intuitive to me, at first sight, anyway, so.... where have I gone wrong
here?

force = mass x (velocity / time) = (mass x velocity) / time = momentum
/ time

F = dp/dt = m*dv/dt = ma

On 03/06/2017 22:32, Cursitor Doom wrote:
Some Newtonian law states that "a body proceeding on a course, blah blah,
provided a force doesn't act on it, blah blah doesn't change and carries
on its own sweet way unmolested." I think that's how it goes anyway.

Now, as we all know, Force = Mass x Acceleration which implies that if I
get hit by something, no matter how heavy, provided it's not changing its
speed, I'll be fine. So if I cross the race track at the TT and in the
process get hit by some bike racer doing 190mph for example (which is not
at all unknown) I'll be totally unharmed. This seems kind of counter-
intuitive to me, at first sight, anyway, so.... where have I gone wrong
here?

The thing which hits you will change its speed. Even if it's a train it
will do - possibly by an undetectable amount, but it will do. Therefore
there is a force, which will be the thing which hurts you.

On 03/06/2017 22:32, Cursitor Doom wrote:
Some Newtonian law states that "a body proceeding on a course, blah blah,
provided a force doesn't act on it, blah blah doesn't change and carries
on its own sweet way unmolested." I think that's how it goes anyway.

Now, as we all know, Force = Mass x Acceleration which implies that if I
get hit by something, no matter how heavy, provided it's not changing its
speed, I'll be fine. So if I cross the race track at the TT and in the
process get hit by some bike racer doing 190mph for example (which is not
at all unknown) I'll be totally unharmed. This seems kind of counter-
intuitive to me, at first sight, anyway, so.... where have I gone wrong
here?


The acceleration you need to worry about is yours - you will go from 0
to significant proportion of the bikes speed, over a very short
distance... The distance basically taken up in the deformation of the
hard heavy bike, and the squashy thing it hits (you can make a fair
guestimate on which will get most bent out of shape!)

So lets say you do that acceleration over a 10cm distance... Lets guess
your terminal speed (no pun intended!) is 60 m/sec, we just need to work
out the acceleration.

We know v^2 = u^2 + 2as, so we get

60^2 = 0 - 2 x a x 0.1

3600 / 0.2 = 18,000 m/s^2 or about 1800g

So if your mass is 90kg, that would mean the bike will need to push you
with a force of 90 x 18000 = 1620 kN to get you up to speed in that 10cm
space.

About as much force as being placed under a 160 tonne weight - its going
to be messy!



--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Yerwot?
I don't understand the question. Remember energy is never destroyed just
changed, so I'm afraid you would be very dead.
Brian

--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
"Cursitor Doom" wrote in message
news
Some Newtonian law states that "a body proceeding on a course, blah blah,
provided a force doesn't act on it, blah blah doesn't change and carries
on its own sweet way unmolested." I think that's how it goes anyway.

Now, as we all know, Force = Mass x Acceleration which implies that if I
get hit by something, no matter how heavy, provided it's not changing its
speed, I'll be fine. So if I cross the race track at the TT and in the
process get hit by some bike racer doing 190mph for example (which is not
at all unknown) I'll be totally unharmed. This seems kind of counter-
intuitive to me, at first sight, anyway, so.... where have I gone wrong
here?

On 03/06/17 22:32, Cursitor Doom wrote:
Some Newtonian law states that "a body proceeding on a course, blah blah,
provided a force doesn't act on it, blah blah doesn't change and carries
on its own sweet way unmolested." I think that's how it goes anyway.

Now, as we all know, Force = Mass x Acceleration which implies that if I
get hit by something, no matter how heavy, provided it's not changing its
speed, I'll be fine. So if I cross the race track at the TT and in the
process get hit by some bike racer doing 190mph for example (which is not
at all unknown) I'll be totally unharmed. This seems kind of counter-
intuitive to me, at first sight, anyway, so.... where have I gone wrong
here?

The bike speed *will* change, by the law of conservation of momentum...

This is implied in the use of the word 'hit' which implies contact.

--
"Socialist governments traditionally do make a financial mess. They
always run out of other people's money. It's quite a characteristic of them"

Margaret Thatcher

wrote:
Since your change in speed is very rapid and your mass not
zero, the force acting on you will be large and painful.

Furthermore, it will be an inelastic collision, which means
that some fraction of the kinetic energy of the bike & rider
will be used to *break* things in addition to speeding them
up.

#Paul

On Sun, 04 Jun 2017 02:33:07 +0100, John Rumm wrote:

So lets say you do that acceleration over a 10cm distance... Lets guess
your terminal speed (no pun intended!) is 60 m/sec, we just need to work
out the acceleration.

We know v^2 = u^2 + 2as, so we get

60^2 = 0 - 2 x a x 0.1

3600 / 0.2 = 18,000 m/s^2 or about 1800g

So if your mass is 90kg, that would mean the bike will need to push you
with a force of 90 x 18000 = 1620 kN to get you up to speed in that 10cm
space.

Noel Coward was a charmer.
As a writer he was brahma.
Velvet, jackets and pyjamas,
had a gay divorce and other dramas.

There ain't half been some clever *******s
(Lucky bleeders, lucky bleeders)
There ain't half been some clever bas-tards.

Van Gough did some eyeball pleasers.
He must have been a pencil squeezer.
He didn't do the Mona Lisa,
That was some Italian geezer.

There ain't half been some clever *******s
(Lucky bleeders, lucky bleeders)
There ain't half been some clever bas-tards.

Einstein can't be classed as witless.
He claimed atoms were the littlest.
When you did a bit of splitting-em-ness
Frighten everybody ****less

There ain't half been some clever *******s.
Probably got help from their mum
(who had help from her mum).
There ain't half been some clever *******s.
Now that we've had some,
let's hope that there's lots more to come.

There ain't half been some clever *******s
(Lucky bleeders, lucky bleeders)
There ain't half been some clever *******s.

- Ian Dury

On Sunday, 4 June 2017 02:33:07 UTC+1, John Rumm wrote:
On 03/06/2017 22:32, Cursitor Doom wrote:
Some Newtonian law states that "a body proceeding on a course, blah blah,
provided a force doesn't act on it, blah blah doesn't change and carries
on its own sweet way unmolested." I think that's how it goes anyway.

Now, as we all know, Force = Mass x Acceleration which implies that if I
get hit by something, no matter how heavy, provided it's not changing its
speed, I'll be fine. So if I cross the race track at the TT and in the
process get hit by some bike racer doing 190mph for example (which is not
at all unknown) I'll be totally unharmed. This seems kind of counter-
intuitive to me, at first sight, anyway, so.... where have I gone wrong
here?


The acceleration you need to worry about is yours - you will go from 0
to significant proportion of the bikes speed, over a very short
distance... The distance basically taken up in the deformation of the
hard heavy bike, and the squashy thing it hits (you can make a fair
guestimate on which will get most bent out of shape!)

So lets say you do that acceleration over a 10cm distance... Lets guess
your terminal speed (no pun intended!) is 60 m/sec, we just need to work
out the acceleration.

We know v^2 = u^2 + 2as, so we get

60^2 = 0 - 2 x a x 0.1

3600 / 0.2 = 18,000 m/s^2 or about 1800g

So if your mass is 90kg, that would mean the bike will need to push you
with a force of 90 x 18000 = 1620 kN to get you up to speed in that 10cm
space.

About as much force as being placed under a 160 tonne weight - its going
to be messy!

.... applied to 1-3 small areas of your body.


NT

On 6/4/2017 12:14 AM, Clive George wrote:
On 03/06/2017 22:32, Cursitor Doom wrote:
Some Newtonian law states that "a body proceeding on a course, blah blah,
provided a force doesn't act on it, blah blah doesn't change and carries
on its own sweet way unmolested." I think that's how it goes anyway.

Now, as we all know, Force = Mass x Acceleration which implies that if I
get hit by something, no matter how heavy, provided it's not changing its
speed, I'll be fine. So if I cross the race track at the TT and in the
process get hit by some bike racer doing 190mph for example (which is not
at all unknown) I'll be totally unharmed. This seems kind of counter-
intuitive to me, at first sight, anyway, so.... where have I gone wrong
here?

The thing which hits you will change its speed. Even if it's a train it
will do - possibly by an undetectable amount, but it will do. Therefore
there is a force, which will be the thing which hurts you.


Correct. Well, strictly speaking you will change its velocity. In the
case of the bike, you are likely to change its direction slightly.

There's the same force on you *and* the bike.

On Sun, 04 Jun 2017 19:45:20 +0100, newshound wrote:

There's the same force on you *and* the bike.

How do these recoil-less guns work, then? They appear to defy the laws of
fizzicks as I misunderstand them.

On 04/06/2017 23:40, Cursitor Doom wrote:
On Sun, 04 Jun 2017 19:45:20 +0100, newshound wrote:

There's the same force on you *and* the bike.

How do these recoil-less guns work, then? They appear to defy the laws of
fizzicks as I misunderstand them.

From what I have read some vent gases to the rear, with the vented
gases counterbalancing the recoil, while others use movement of a piston
by the gases to do the same.

SteveW

On 04/06/2017 23:40, Cursitor Doom wrote:
On Sun, 04 Jun 2017 19:45:20 +0100, newshound wrote:

There's the same force on you *and* the bike.

How do these recoil-less guns work, then? They appear to defy the laws of
fizzicks as I misunderstand them.

Something goes in the opposite direction to the bullet. If you can't see
it it'll be a gas.

On 04/06/2017 23:40, Cursitor Doom wrote:
On Sun, 04 Jun 2017 19:45:20 +0100, newshound wrote:

There's the same force on you *and* the bike.

How do these recoil-less guns work, then? They appear to defy the laws of
fizzicks as I misunderstand them.

Most are rocket launcher style tubes... so the force for accelerating
the projectile is not coupled to the "gun"




--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 04/06/17 23:40, Cursitor Doom wrote:
On Sun, 04 Jun 2017 19:45:20 +0100, newshound wrote:

There's the same force on you *and* the bike.

How do these recoil-less guns work, then? They appear to defy the laws of
fizzicks as I misunderstand them.

enough gas is ejected backwards to counteract the bullet going forward

--
€œSome people like to travel by train because it combines the slowness of
a car with the cramped public exposure of €¨an airplane.€�

Dennis Miller

On Saturday, 3 June 2017 23:12:00 UTC+1, wrote:
On Saturday, 3 June 2017 22:51:05 UTC+1, Andy Burns wrote:
Cursitor Doom wrote:

Now, as we all know, Force = Mass x Acceleration which implies that if I
get hit by something, no matter how heavy, provided it's not changing its
speed, I'll be fine.

It's the change in *your* speed (accelerating from near stationary to
near the bike's speed in a fraction of a second) that will hurt a bit.

Of course the bike will also decelerate as it hits you (conservation of
momentum).

Since your change in speed is very rapid and your mass not zero, the force acting on you will be large and fun

FTFY

Pictures or it doesn't brmmmm happen!

NT

Cursitor Doom wrote
newshound wrote

There's the same force on you *and* the bike.

How do these recoil-less guns work, then?

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

They appear to defy the laws of fizzicks

Nope.

as I misunderstand them.

THATS the problem.

On Tue, 06 Jun 2017 05:16:30 +1000, Rod Speed wrote:

Cursitor Doom wrote
newshound wrote

There's the same force on you *and* the bike.

How do these recoil-less guns work, then?

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

They appear to defy the laws of fizzicks

Nope.

as I misunderstand them.

THATS the problem.

Nobody asked YOU.

On 05/06/2017 23:44, Cursitor Doom wrote:
On Tue, 06 Jun 2017 05:16:30 +1000, Rod Speed wrote:

Cursitor Doom wrote
newshound wrote

There's the same force on you *and* the bike.

How do these recoil-less guns work, then?

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

They appear to defy the laws of fizzicks

Nope.

as I misunderstand them.

THATS the problem.

Nobody asked YOU.


You asked everyone in the world.

On Monday, 5 June 2017 01:24:06 UTC+1, wrote:
wrote:
Since your change in speed is very rapid and your mass not
zero, the force acting on you will be large and painful.

Furthermore, it will be an inelastic collision, which means
that some fraction of the kinetic energy of the bike & rider
will be used to *break* things in addition to speeding them
up.

#Paul

Heat will be generated too from an impact.

On 06/06/17 13:09, whisky-dave wrote:
On Monday, 5 June 2017 01:24:06 UTC+1, wrote:
wrote:
Since your change in speed is very rapid and your mass not
zero, the force acting on you will be large and painful.

Furthermore, it will be an inelastic collision, which means
that some fraction of the kinetic energy of the bike & rider
will be used to *break* things in addition to speeding them
up.

#Paul

Heat will be generated too from an impact.

heat is random kinetic energy of molecules..

--
€œSome people like to travel by train because it combines the slowness of
a car with the cramped public exposure of €¨an airplane.€�

Dennis Miller

On Tuesday, 6 June 2017 13:30:25 UTC+1, The Natural Philosopher wrote:
On 06/06/17 13:09, whisky-dave wrote:
On Monday, 5 June 2017 01:24:06 UTC+1, wrote:
wrote:
Since your change in speed is very rapid and your mass not
zero, the force acting on you will be large and painful.

Furthermore, it will be an inelastic collision, which means
that some fraction of the kinetic energy of the bike & rider
will be used to *break* things in addition to speeding them
up.

#Paul

Heat will be generated too from an impact.

heat is random kinetic energy of molecules..


So......
When two things collide the energy can be transformed into heat.

On 06/06/17 16:55, whisky-dave wrote:
On Tuesday, 6 June 2017 13:30:25 UTC+1, The Natural Philosopher wrote:
On 06/06/17 13:09, whisky-dave wrote:
On Monday, 5 June 2017 01:24:06 UTC+1, wrote:
wrote:
Since your change in speed is very rapid and your mass not
zero, the force acting on you will be large and painful.

Furthermore, it will be an inelastic collision, which means
that some fraction of the kinetic energy of the bike & rider
will be used to *break* things in addition to speeding them
up.

#Paul

Heat will be generated too from an impact.

heat is random kinetic energy of molecules..


So......
When two things collide the energy can be transformed into heat.

No., The heat already IS kinetic energy.


--
"Corbyn talks about equality, justice, opportunity, health care, peace,
community, compassion, investment, security, housing...."
"What kind of person is not interested in those things?"

"Jeremy Corbyn?"

"dennis@home" wrote in message
web.com...

On 05/06/2017 23:44, Cursitor Doom wrote:
On Tue, 06 Jun 2017 05:16:30 +1000, Rod Speed wrote:

Cursitor Doom wrote
newshound wrote

There's the same force on you *and* the bike.

How do these recoil-less guns work, then?

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

They appear to defy the laws of fizzicks

Nope.

as I misunderstand them.

THATS the problem.

Nobody asked YOU.


You asked everyone in the world.

Bull****. There are not 7 plus billion people reading this group.

On Tue, 06 Jun 2017 19:31:50 +0100, Richard wrote:

Bull****. There are not 7 plus billion people reading this group.

Why don't you get back into bed? (repeat)

Some of Buddy Holly, the working folly
Good Golly Miss Molly, and boats
Hammersmith Palais, the Bolshoi Ballet
Jump back in the alley add nanny goats

18-wheeler Scammels, Domineker camels
All other mammals plus equal votes
Seeing Picadilly, Fanny Smith and Willy
Being rather silly, and porridge oats

A bit of grin and bear it, a bit of come and share it
You're welcome we can spare it - yellow socks
To short to be haughty, too nutty to be naughty
Going on forty - no electric shocks

The juice of a carrot, the smile of the parrot
A little drop of claret, anything that rocks
Elvis and Scotty, days when I ain't spotty
Sitting on the potty, curing smallpox

Reasons to be cheerful, part 3
Reasons to be cheerful, part 3
Reasons to be cheerful, part 3
Reasons to be cheerful - 1, 2, 3

Reasons to be cheerful, part 3

Health service glasses, gigolos and brasses
Round or skinny bottoms

Take your mum to Paris, lighting up the chalice
Wee Willy Harris!
Bantu Steven Biko, listening to Riko
Harpo, Graucho, Chico

Cheddar cheese and pickle, the Vincent motorsickle
Slap-and-tickle
Woody Allen, Dali, Dimitri and Pasquale
Balabalabala and Volare

Something nice to study, phoning up a buddy
Being in my nuddy
Saying okey-dokey, singalonga Smokey
Coming out of Chokey

John Coltrane's soprano, Adi Celantano
Bonar Colleano

Reasons to be cheerful, part 3
Reasons to be cheerful, part 3
Reasons to be cheerful, part 3
Reasons to be cheerful - 1, 2, 3

Yes, yes, dear, dear, perhaps next year
Or maybe even never
In which case...

Reasons to be cheerful, part 3
Reasons to be cheerful, part 3
Reasons to be cheerful, part 3
Reasons to be cheerful - 1, 2, 3

- Ian Dury

On Tuesday, 6 June 2017 18:07:14 UTC+1, The Natural Philosopher wrote:
On 06/06/17 16:55, whisky-dave wrote:
On Tuesday, 6 June 2017 13:30:25 UTC+1, The Natural Philosopher wrote:
On 06/06/17 13:09, whisky-dave wrote:
On Monday, 5 June 2017 01:24:06 UTC+1, wrote:
wrote:
Since your change in speed is very rapid and your mass not
zero, the force acting on you will be large and painful.

Furthermore, it will be an inelastic collision, which means
that some fraction of the kinetic energy of the bike & rider
will be used to *break* things in addition to speeding them
up.

#Paul

Heat will be generated too from an impact.

heat is random kinetic energy of molecules..


So......
When two things collide the energy can be transformed into heat.

No., The heat already IS kinetic energy.

but it's not heat, it's kinetic energy, did you not know.