Question for the resident boffins.....

[Ixion]

..
Also taking the theory of relativitiy, as I've never been that fast I'm not sure what happens as you approach the speed of light. I've heard it slows down time, but I'm not sure about weight.

,,.

I'm just waiting for someone to tell y' that if y'had a Suzuki you would have been that fast.

[yungatart]

Lets not confuse speed with velocity or weight with mass. If I remember my 4th form science lessons (and, lets face it, it was a loong time ago..),they are not the same thing. It could have a bearing on what you, the esteemed boffins, are trying to explain to the poor uneducated plebs like me..

[Waylander]

It was all very annoying when they tought us it was centafugal force one year then the next suddenly centrafugal force no longer exhists and centripetel is the word of the day. Can't these 'scientists' make up thier mind?

Damn braniacs getting revenge for all that nerd shit in highschool.

[Harry33]

This is all neat and stuff but does anyone know what the 13 herbs and spices are?

[MSTRS:Me]

This is all neat and stuff but does anyone know what the 13 herbs and spices are?

Who cares.....it's still cat underneath.

[Skyryder]

The scales would require some sort of downwards motion to cause a reading, if there was insufficient time for that motion to occur fully then I suppose you would get a lighter reading.
If the scales had a weigh-bridge of say 50 metres long you would then get a true reading.

No you would not. Velocity or forward movement reduces weight at point of contact. This is one of the few things that still sticks from my science class, years ago. It's one of the reasons cars slide off the road when going round corners at speed. They become too light and lose traction and keep on travelling in the direction of momentum.

It's the reason racing cars have foils so that wind pressure helps to 'push' the car down on the tarmac.

Skyryder

[Skyryder]

This http://regentsprep.org/Regents/physi...if/centrif.htm
explains the difference between Centrapetal and Centrfugal Force. The two are not the same.

Skyryder

[Jamezo]

It was all very annoying when they tought us it was centafugal force one year then the next suddenly centrafugal force no longer exhists and centripetel is the word of the day. Can't these 'scientists' make up thier mind?

Damn braniacs getting revenge for all that nerd shit in highschool.

As already mentioned, "centrifugal force" is a disgusting laymans term for an observation of straight-line force about a rotating central frame of reference.

It's all a borgeious conspiracy.

[marty]

a vehicle (and everything for that matter) is being held on the earth at 1g. if you exceed 1g in a sidewise or upwards direction the vehicle will head there.

what is being said here means that a 4wd vehicle, on a 4wd dyno/treadmill, when it has it's wheels rotating, will weigh less? don't think so - it still will exert 1g downwards.

[scumdog]

No you would not. Velocity or forward movement reduces weight at point of contact. This is one of the few things that still sticks from my science class, years ago. It's one of the reasons cars slide off the road when going round corners at speed. They become too light and lose traction and keep on travelling in the direction of momentum.

It's the reason racing cars have foils so that wind pressure helps to 'push' the car down on the tarmac.

Skyryder

It's not because they get 'lighter' - it's because the lateral force exceeds the downwards force (gravity)

To look at it another way when a car is slowing down it should get heavier according to your theory - so if you slow down as you go around a corner the car should stick better and grip the road - not sledge straight ahead off the road?

And yes, airfoils do 'push' a car downwards - to overcome the sideways pull of lateral forces when cornering AND at high speeds to stop 'lift' due to airflow over the body.

[marty]

geez SD - that's a late night on the riviera!

[marty]

the resultant component of weight does shift as the car moves around, at a standstill it is right below the c of g, but apply an acelleration in any direction (or multiple directions) and the resultant vector will move. the total mass doesn't change, so the weight of the vehicle doesn't change, unless there is a substantial (that is, measurable) change in altitude, to one which is beginning to realise a change in the earth's force due to gravity

[thealmightytaco]

Any centripetal force from the wheels act equally up as they do down so there wont be any weight change, unless you're nearing the speed of light and E=mc^2 is coming into play bu that's another story.

And the original q about whether the centripetal acceleration on the wheel will deform the tyre more = bigger contact patch; This is why you buy speed rated tyres, for cars at least, I'm not sure about bikes, I havent had to buy any yet, but the tyres can expand from the force and all but want to leave the rim if they're not up to task. But in real life (with a properly rated tyre) the extra deformation from centripetal force compared to you sitting on the bike would be minimal against a tyre inflated to 30psi. Really.

[scumdog]

geez SD - that's a late night on the riviera!

Yeah well home from quelling riots, rescuing virgins, busting drunks, etc etc and needed an 'unwind' before hitting the sack.

[MSTRS:Me]

And the original q about whether the centripetal acceleration on the wheel will deform the tyre more .....

Sorry, you misunderstand. That was not the original question. Skyrider seems to understand where I was coming from. Perhaps I worded it ambiguously.
The question (reworded) was - does the pressure exerted on the contact patch lighten as a bike gets faster??
Everything has a given mass, but it's weight is subject to gravity and other forces, so can *alter*. The braking scenario is one - whereby impetus denied translates to a greatly increased downward pressure on the front contact patch, thereby making the attached bike 'weigh more'. Also when accelerating, the same force applies to the rear contact patch, for as long as acceleration continues.