Fish-Finger-er Posted January 9, 2012 Report Share Posted January 9, 2012 (edited) It would weigh nothing, but it's mass would increase. Making the bike harder to move in every direction that isn't against gravity. I wonder what the mass of a 1000 liters of helium would me compared to the mass of a 10kg bike. it would weigh more, as itd be pressurised, helium still has a mass, as the pressure increases so does the mass,eventually its mass relative to its volume exceeds that of air, and it then has an actual weight on the scales in the regular unpressurised atmosphere. Edited January 9, 2012 by Fish-Finger-er Quote Link to comment Share on other sites More sharing options...
JT! Posted January 9, 2012 Report Share Posted January 9, 2012 So at what pressure does helium become the same density as air? Quote Link to comment Share on other sites More sharing options...
ZeroMatt Posted January 9, 2012 Report Share Posted January 9, 2012 So at what pressure does helium become the same density as air? ~100 psi, would be very much dependent on temperatures though. Quote Link to comment Share on other sites More sharing options...
monkeyseemonkeydo Posted January 9, 2012 Report Share Posted January 9, 2012 The realms between joking and serious appear to be blurring! 1 Quote Link to comment Share on other sites More sharing options...
Sam Nichols Posted January 9, 2012 Report Share Posted January 9, 2012 This is all well and good, but can a fly stop a train? Quote Link to comment Share on other sites More sharing options...
James Quigley Posted January 9, 2012 Report Share Posted January 9, 2012 Can I just say, even if it did make it ever so slightly lighter, it wouldn't be enough for the scales they use to register the difference. So ultimately your sweeties will cost the same, but you'd have spent more time fannying about with baloons and compressed helium cannisters. Quote Link to comment Share on other sites More sharing options...
Muel Posted January 9, 2012 Report Share Posted January 9, 2012 But do the sweeties take off? Quote Link to comment Share on other sites More sharing options...
N.Wood Posted January 9, 2012 Report Share Posted January 9, 2012 Another thing to consider is it's probably better value to buy those foam prawns than, say, a gobstopper due to the weight involved. Quote Link to comment Share on other sites More sharing options...
Fish-Finger-er Posted January 9, 2012 Report Share Posted January 9, 2012 flying saucers *** 1 Quote Link to comment Share on other sites More sharing options...
LukasMcNeal Posted January 9, 2012 Report Share Posted January 9, 2012 Another thing to consider is it's probably better value to buy those foam prawns than, say, a gobstopper due to the weight involved. Another thing to consider is the air in the foam sweets could then be replaced with helium thus making it even lighter... Quote Link to comment Share on other sites More sharing options...
Krisboats Posted January 9, 2012 Report Share Posted January 9, 2012 Might be the first time I've ever felt OG on this forum! But what I never got about pressurized helium is that it's lighter than air because it's less dense? So helium pressurized would make it more dense and therefor heavier? When you pressurize helium it becomes colder, incredibly so (opening a gas valve to full will freeze the pvc piping attached to the end and the nozzle will ice over). Helium loses bouancy when cool and as such you have both dense helium and cold factoring into it's lack of bouancy. For point of reference, 2 50L canisters compressed to 200bar each will weigh approximately 65-70kg per cannister. When uncompressed and put into a balloon the helium will have enough lift to gently pull both cannisters around (in normal operating conditions of 10+degrees C and light winds) and will almost lift a single cannister off the floor. In dubai i nearly got lifted off a building while trying to secure a balloon with nearly 3 cannisters inside. In reference to the original question yes it will make it lighter, although only marginaly. Quote Link to comment Share on other sites More sharing options...
Simpson Posted January 10, 2012 Report Share Posted January 10, 2012 (edited) I think this situation needs a Simps with some complicated maths to find the perfect cost of helium/saving made on sweets ratio. Hahaha na no real wise words, been said already exaggerate the sizes, a huge helium balloon and a small bag of sweets would lift the bag. So yes it could "lighten" your bag and its not a stupid comment to make, but in reality the difference would be very marginal. its explained further here, http://en.wikipedia.org/wiki/Lifting_gas so you could work out how much helium it would take to lift your 300g of sweets but I cant, all day revision means my maths ability is below a 5 year olds, took me half an hour to sort a friends question about logs today haha Edit to lift 250g of sweets you would need about 40 grams of helium how much volume this would occupy would depend on temperature and pressure. Edited January 10, 2012 by Simpson Quote Link to comment Share on other sites More sharing options...
konstant Posted January 10, 2012 Report Share Posted January 10, 2012 What you'd need for some real money saving is some sort of high pressure vessel filled with helium at high pressure. More helium = more floaty. P.S. If you've been on this forum less than 5 years, you probably won't get this reference Brilliant. interesting concept, I wonder if that could be made to work on bike frames, maybe fill the tubes with helium at like 10bar, and youve got a bike that weights nothing, possibly?!?! Quote Link to comment Share on other sites More sharing options...
Shaun H Posted January 10, 2012 Report Share Posted January 10, 2012 When you pressurize helium it becomes colder, incredibly so (opening a gas valve to full will freeze the pvc piping attached to the end and the nozzle will ice over). Helium loses bouancy when cool and as such you have both dense helium and cold factoring into it's lack of bouancy. A gas actually does the opposite when you pressurise it. The equation PV=nRT dictates this. When you open the valve on a bottle the helium is being depressurised, hence the cold, ice, etc, etc 1 Quote Link to comment Share on other sites More sharing options...
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