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is this physically possible? - Printable Version

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is this physically possible? by spokes on 03-15-2005 at 09:39 PM

ok i read somewhere that you cannot go from forward motion to backward motion without stoppin (even if its for the smallest amount of time).

so if that top part is true then this below should be true

if a fly hit your car window, it would splatter and start goin backwards? but doesnt it have to stop first?

meaning it would stop the whole car (for small time) otherwise smash the windscreen?

just wondering, me and my friend are having a debate about it, lol

RE: is this physically possible? by SikStyles on 03-15-2005 at 09:48 PM

it is impossible because when a fly hits the windshield then as soon as it hits its splats and the car will take it from there..but even tho its impossible

RE: is this physically possible? by Jhrono on 03-15-2005 at 09:48 PM

Flys do smash against cars and stay there sticked due to the cars force, because they are heading to the opposite direction..they would stop cars cause they are more faster..

RE: is this physically possible? by King For A Day on 03-15-2005 at 09:54 PM

hmm i get confused easily so ill geuss and say no

RE: is this physically possible? by NiteMare on 03-15-2005 at 09:58 PM

this is completly posable, i do it all the time in hockey

as i skate backwards i turn my saktes to the side, spin my feet around and then  keep turning forwards

its may sound weird, but its all one motion with out stoping

RE: is this physically possible? by Jhrono on 03-15-2005 at 10:02 PM

quote:
Originally posted by NiteMare

its may sound weird, but its all one motion with out stoping

Your right but your movement is a 180º(half circle) to turn around...what he means is to change from forward motion and suddenly start walking backward...there's allways a stop, mainly cause you arent made for that(i think)
RE: is this physically possible? by MC.POP on 03-15-2005 at 10:06 PM

quote:
Originally posted by spokes
ok i read somewhere that you cannot go from forward motion to backward motion without stoppin (even if its for the smallest amount of time).

so if that top part is true then this below should be true

if a fly hit your car window, it would splatter and start goin backwards? but doesnt it have to stop first?

meaning it would stop the whole car (for small time) otherwise smash the windscreen?

just wondering, me and my friend are having a debate about it, lol
ok when u first said the first quote that means the same object going forwards then backwards but when u said about the car and fly that is collision ans ia whole different thing ;)
RE: is this physically possible? by CookieRevised on 03-15-2005 at 10:52 PM

quote:
Originally posted by MC.POP
when u first said the first quote that means the same object going forwards then backwards but when u said about the car and fly that is collision ans ia whole different thing ;)
nope, it is exactly the same thing: reaction of forces on each other.
laws:
"for every action there is a reaction"
"a force will not dissepear by itself, it has to go somewhere"



quote:
Originally posted by spokes
ok i read somewhere that you cannot go from forward motion to backward motion without stoppin (even if its for the smallest amount of time).

so if that top part is true then this below should be true

if a fly hit your car window, it would splatter and start goin backwards? but doesnt it have to stop first?

meaning it would stop the whole car (for small time) otherwise smash the windscreen?

just wondering, me and my friend are having a debate about it, lol
You actualy already know the correct answer ;)

It IS indeed true that it is impossible to go forward and immediatly go backward without stopping.

This is a nature law. If you want to turn the positive force around which makes you go farwards, at one point the force will be 0 (stopped), before it will be negative (backwards).

This is also true for the fly!! The fly _indeed_ slows the car down!!! But the force that the fly has is so small compared to the force of the car that it is as good as 0 (but not completely 0!)

######force car######>       <..force fly..
eg: Fc = 10000                              Ff = 0.1

####force car####><force fly
eg: Fc = 10000 - 0.1 = 9999.9         Ff = 0
=> the car slowed down because the forward force has been reduced by the forward force of the fly

This nature law is simply called "Action/Reaction". For every action there is an opposite reaction


RE: is this physically possible? by Plik on 03-15-2005 at 10:53 PM

The fly is stoped, in relativity to the car.

Anyway, think of a graph showing the flys speed to go from a certain speed in one direction, to a splating and going the same way as a car, it has to deaccelarate then accelerate in the other dirrection.

If i feel bored i might make a picture

RE: is this physically possible? by CookieRevised on 03-15-2005 at 10:59 PM

quote:
Originally posted by Madman
The fly is stoped, in relativity to the car.
not in relativity, it is stopped period. Time is a factor in motion, it can't be excluded. At one point in time the fly will have no motion at all.

1) car and fly approaches each other:
car has forward motion
fly has forward motion

2) collission occurs:
car has still forward motion (but a little bit less, but not 0)
fly has been stopped, relativly to everything!

3) right after collission
car has still the same reduced forward motion
fly bounces back => reversed motion

quote:
Originally posted by Madman
Anyway, think of a graph showing the flys speed to go from a certain speed in one direction, to a splating and going the same way as a car, it has to deaccelarate then accelerate in the other dirrection.
Absolutely correct
RE: is this physically possible? by NiteMare on 03-15-2005 at 11:02 PM

i see

so if you take a graph of the flys vector (speed/direction vs time
you would see the fly traveling 1 kph [north], then suddenly its going 6 kph [south], if you look close enough you'll see that at one point the fly has slown down enough that is has stoped, then its starts in th other direction