Will a lake jump hurt my blk mrkt 357?

PB Forum :: Dirt Jumping & Street
Will a lake jump hurt my blk mrkt 357?
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flag mike-smith
Posted: Feb 28, 2010 at 16:39 Quote
freeride-idiot wrote:
if you belive wat i have said to be incorect i think you should try harder at school or perhaps get a degree in mechanical engineering like i have
cowieuk wrote:
freeride-idiot wrote:
Attention very few bikes float in most cases the mass of the frame and components outweigh the mass of water displaced by the air in the tires thus THEY SINK!!
Attention the more air you put in the tire the density increases thus they become LESS BUOYANT!!Facepalm Madder Dead Horse Dead Horse Dead Horse

run along and do your homework

Not true really at all. you do some homework.

But yeah use a beater bike for lake jumps with inner tubes through spokes.

wrongwrongwrongwrongwrongwrongwrong.

cowieuk is correct.
Inflating your tyres DOES make your bike more bouyant. Lets have an examlpe here : Im in a swimming pool. I take a deep breath and attempt to swim down but have great difficulty in doing so as the air in my lungs is forcing me back to the surface. therefore, more air makes me more bouyant!

the density cannot increase if i put more air in my tyres as air does not weigh anything!

you know id expect someone with a degree in mechanical engineering to know that air is weightless, or is that just too advanced?
*note* i have qualifications in mechanical, electrical and aeronautical engineering so im not just some stupid kid whos proving you wrong..although to be honest, i might aswell be.

P.S. congrats on spelling Bouyant wrong.
flag ginj
Posted: Feb 28, 2010 at 16:42 Quote
Just tie a bottle to a thick piece of rope/chain. Your bike sinks, the bottle floats (make sure the rope is long enough), and then you can just pull it up again.
flag mgolland45
Posted: Feb 28, 2010 at 17:13 Quote
mike-smith wrote:
freeride-idiot wrote:
if you belive wat i have said to be incorect i think you should try harder at school or perhaps get a degree in mechanical engineering like i have
cowieuk wrote:


Not true really at all. you do some homework.

But yeah use a beater bike for lake jumps with inner tubes through spokes.

wrongwrongwrongwrongwrongwrongwrong.

cowieuk is correct.
Inflating your tyres DOES make your bike more bouyant. Lets have an examlpe here : Im in a swimming pool. I take a deep breath and attempt to swim down but have great difficulty in doing so as the air in my lungs is forcing me back to the surface. therefore, more air makes me more bouyant!

the density cannot increase if i put more air in my tyres as air does not weigh anything!

you know id expect someone with a degree in mechanical engineering to know that air is weightless, or is that just too advanced?
*note* i have qualifications in mechanical, electrical and aeronautical engineering so im not just some stupid kid whos proving you wrong..although to be honest, i might aswell be.

P.S. congrats on spelling Bouyant wrong.
compressed air Ie: air in bike tires has a higher density air isnt weightless, it might weigh very little but it isnt weightless
flag pbuser102331
Posted: Feb 28, 2010 at 17:20 Quote
^^^ Hence the need for hydrogen/helium in air ships.
flag asdfasdf
Posted: Feb 28, 2010 at 17:20 Quote
mike-smith wrote:

wrongwrongwrongwrongwrongwrongwrong.

cowieuk is correct.
Inflating your tyres DOES make your bike more bouyant. Lets have an examlpe here : Im in a swimming pool. I take a deep breath and attempt to swim down but have great difficulty in doing so as the air in my lungs is forcing me back to the surface. therefore, more air makes me more bouyant!

the density cannot increase if i put more air in my tyres as air does not weigh anything!

you know id expect someone with a degree in mechanical engineering to know that air is weightless, or is that just too advanced?
*note* i have qualifications in mechanical, electrical and aeronautical engineering so im not just some stupid kid whos proving you wrong..although to be honest, i might aswell be.

P.S. congrats on spelling Bouyant wrong.

Air has mass, if a tyre with a volume of about 7 litres (just a guess to make the maths simpler) and is at 45 psi (about 3 atm) the tyre will contain about 30 g of air.

This is because one mole of air has a volume of 22 litres at stp and 1 atm, so at 3 atm it will have a volume of about 7 litres, and as 1 mol of air has a mass of 30 g you will have 30 g of air in the tyre.

If you double the pressure to 90 psi (6 atm) one mole of air will occupy 3.5 litres so the tyre will contain 2 moles of air which is 60 g meaning air in the tyre is more dense but hte 30 g difference will be insignificant on the scale of a bike.
flag ginj
Posted: Feb 28, 2010 at 17:22 Quote
Close, but its 24 litres Wink . Not that it makes much difference in your example. Simple fact is that tyre air alone CANNOT keep a bike afloat.
flag pbuser102331
Posted: Feb 28, 2010 at 17:22 Quote
asdfasdf wrote:
mike-smith wrote:

wrongwrongwrongwrongwrongwrongwrong.

cowieuk is correct.
Inflating your tyres DOES make your bike more bouyant. Lets have an examlpe here : Im in a swimming pool. I take a deep breath and attempt to swim down but have great difficulty in doing so as the air in my lungs is forcing me back to the surface. therefore, more air makes me more bouyant!

the density cannot increase if i put more air in my tyres as air does not weigh anything!

you know id expect someone with a degree in mechanical engineering to know that air is weightless, or is that just too advanced?
*note* i have qualifications in mechanical, electrical and aeronautical engineering so im not just some stupid kid whos proving you wrong..although to be honest, i might aswell be.

P.S. congrats on spelling Bouyant wrong.

Air has mass, if a tyre with a volume of about 7 litres (just a guess to make the maths simpler) and is at 45 psi (about 3 atm) the tyre will contain about 30 g of air.

This is because one mole of air has a volume of 22 litres at stp and 1 atm, so at 3 atm it will have a volume of about 7 litres, and as 1 mol of air has a mass of 30 g you will have 30 g of air in the tyre.

If you double the pressure to 90 psi (6 atm) one mole of air will occupy 3.5 litres so the tyre will contain 2 moles of air which is 60 g meaning air in the tyre is more dense but hte 30 g difference will be insignificant on the scale of a bike.

Does that mean it will float then.?
flag asdfasdf
Posted: Feb 28, 2010 at 17:26 Quote
ginj wrote:
Close, but its 24 litres Wink . Not that it makes much difference in your example. Simple fact is that tyre air alone CANNOT keep a bike afloat.

Yes , I just used the wrong one 22 litres is at zero degrees rather than 25 degrees, so its probably more appropriate at the moment anyway.
flag asdfasdf
Posted: Feb 28, 2010 at 17:29 Quote
marquis wrote:

Does that mean it will float then.?

I don't know the actual volume of the tyres but it means that the tyre pressure won't make a difference.
flag pbuser102331
Posted: Feb 28, 2010 at 17:30 Quote
asdfasdf wrote:
marquis wrote:

Does that mean it will float then.?

I don't know the actual volume of the tyres but it means that the tyre pressure won't make a difference.

Salute
flag ginj
Posted: Feb 28, 2010 at 17:32 Quote
I was just being pedantic Fab .
flag bikerboywill
FL
Posted: Mar 1, 2010 at 9:46 Quote
mike-smith wrote:
freeride-idiot wrote:
if you belive wat i have said to be incorect i think you should try harder at school or perhaps get a degree in mechanical engineering like i have
cowieuk wrote:


Not true really at all. you do some homework.

But yeah use a beater bike for lake jumps with inner tubes through spokes.

wrongwrongwrongwrongwrongwrongwrong.

cowieuk is correct.
Inflating your tyres DOES make your bike more bouyant. Lets have an examlpe here : Im in a swimming pool. I take a deep breath and attempt to swim down but have great difficulty in doing so as the air in my lungs is forcing me back to the surface. therefore, more air makes me more bouyant!

the density cannot increase if i put more air in my tyres as air does not weigh anything!

you know id expect someone with a degree in mechanical engineering to know that air is weightless, or is that just too advanced?
*note* i have qualifications in mechanical, electrical and aeronautical engineering so im not just some stupid kid whos proving you wrong..although to be honest, i might aswell be.

P.S. congrats on spelling Bouyant wrong.

thats what i was trying to say, but me fail at english so it is unpossible to get anything that makes sense coming out of my mouth but thats what was in my head, but seriously lol
flag freeride-idiot
Posted: Mar 1, 2010 at 14:46 Quote
so you think air is weightless then ?? i think i must explain in laymens terms for you example at work we order a bottle of gas presurised gas in a bottle is bought by the litre or by the kilogram as is marked on the bottle if you get an empty bottle and a full bottle then try to pick them up you will very quickly learn that air does weigh somthing
you will also find that when you take a breath the air in your lungs is at atmospheric pressure not 30-60psi like a bike tire
unless you run at a higher psi than everybody else lol are pressurised
wow a degree in mechanical/electrical and aeronautical degrees that must have taken some time to study for in 3 vastly different areas this must have taken oooh 20 years?? oh but your only 19?????
i would expect especialy with an aeronautical degree you of all people should know that air definatly does weigh somthing?
mike-smith wrote:
freeride-idiot wrote:
if you belive wat i have said to be incorect i think you should try harder at school or perhaps get a degree in mechanical engineering like i have
cowieuk wrote:


Not true really at all. you do some homework.

But yeah use a beater bike for lake jumps with inner tubes through spokes.

wrongwrongwrongwrongwrongwrongwrong.

cowieuk is correct.
Inflating your tyres DOES make your bike more bouyant. Lets have an examlpe here : Im in a swimming pool. I take a deep breath and attempt to swim down but have great difficulty in doing so as the air in my lungs is forcing me back to the surface. therefore, more air makes me more bouyant!

the density cannot increase if i put more air in my tyres as air does not weigh anything!

you know id expect someone with a degree in mechanical engineering to know that air is weightless, or is that just too advanced?
*note* i have qualifications in mechanical, electrical and aeronautical engineering so im not just some stupid kid whos proving you wrong..although to be honest, i might aswell be.

P.S. congrats on spelling Bouyant wrong.
flag freeride-idiot
Posted: Mar 1, 2010 at 14:52 Quote
anyhoo look any doubt just tie somthing that floats to your bikes so you dont lose them
it might look a bit c**P but walking home is realy crap
ps sorry if iv anoyed anyone with my rantingsSalute
flag mike-smith
Posted: Mar 1, 2010 at 14:57 Quote
freeride-idiot wrote:
so you think air is weightless then ?? i think i must explain in laymens terms for you example at work we order a bottle of gas presurised gas in a bottle is bought by the litre or by the kilogram as is marked on the bottle if you get an empty bottle and a full bottle then try to pick them up you will very quickly learn that air does weigh somthing
you will also find that when you take a breath the air in your lungs is at atmospheric pressure not 30-60psi like a bike tire
unless you run at a higher psi than everybody else lol are pressurised
wow a degree in mechanical/electrical and aeronautical degrees that must have taken some time to study for in 3 vastly different areas this must have taken oooh 20 years??
i would expect especialy with an aeronautical degree you of all people should know that air definatly does weigh somthing?

My point is that you said that if you increase the pressure in your tyres it would make a bike significantly heavier and therefore sink just as fast? an increase in pressure would increase the mass of air which would aid bouyancy.

and i said qualifications, not degrees. I have a basic to adequate understanding of what im talking about, otherwise i wouldnt have bothered.
Also, we do not have to know about weight of air in the aeronautical subject, just the density

 


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