Things you always wanted to know the answer to [Vol. 5]

[Dr Jekyll]

Johnspex said:

RATATTAK said:

Johnspex said:

Can anyone tell me the formula for working out how fast, in mph, a point on the tread of my tyre is travelling? Please.

Rotationally or linearly ?b

Er, not sure what that means. A point on the outer circumference of the tyre must have a speed in mph, surely. It must also be faster than one of the wheel nuts as it travels a greater distance for each revolution. If, say, the tyre circumference is 1 metreand it goes round once every second it is travelling 1m per sec. The wheel nut which part of a circle of, say, 50cm circumference will only travel 50cm per sec.

I read once about the phenomenal speed the rim of the wheels on Bloodhound SSC will travel .

That's the rotational speed, there is also the linear speed along the road.

[RATATTAK]

Johnspex said:

RATATTAK said:

Johnspex said:

Can anyone tell me the formula for working out how fast, in mph, a point on the tread of my tyre is travelling? Please.

Rotationally or linearly ?b

Er, not sure what that means. A point on the outer circumference of the tyre must have a speed in mph, surely. It must also be faster than one of the wheel nuts as it travels a greater distance for each revolution. If, say, the tyre circumference is 1 metreand it goes round once every second it is travelling 1m per sec. The wheel nut which part of a circle of, say, 50cm circumference will only travel 50cm per sec.

I read once about the phenomenal speed the rim of the wheels on Bloodhound SSC will travel .

Yeah you've got it, so the next thing we need to know is the diameter of the tyre.

[K12beano]

RATATTAK said:

Johnspex said:

RATATTAK said:

Johnspex said:

Can anyone tell me the formula for working out how fast, in mph, a point on the tread of my tyre is travelling? Please.

Rotationally or linearly ?b

Er, not sure what that means. A point on the outer circumference of the tyre must have a speed in mph, surely. It must also be faster than one of the wheel nuts as it travels a greater distance for each revolution. If, say, the tyre circumference is 1 metreand it goes round once every second it is travelling 1m per sec. The wheel nut which part of a circle of, say, 50cm circumference will only travel 50cm per sec.

I read once about the phenomenal speed the rim of the wheels on Bloodhound SSC will travel .

Yeah you've got it, so the next thing we need to know is the diameter of the tyre.

Is it on a conveyor belt?

[Dr Jekyll]

K12beano said:

RATATTAK said:

Johnspex said:

RATATTAK said:

Johnspex said:

Can anyone tell me the formula for working out how fast, in mph, a point on the tread of my tyre is travelling? Please.

Rotationally or linearly ?b

Er, not sure what that means. A point on the outer circumference of the tyre must have a speed in mph, surely. It must also be faster than one of the wheel nuts as it travels a greater distance for each revolution. If, say, the tyre circumference is 1 metreand it goes round once every second it is travelling 1m per sec. The wheel nut which part of a circle of, say, 50cm circumference will only travel 50cm per sec.

I read once about the phenomenal speed the rim of the wheels on Bloodhound SSC will travel .

Yeah you've got it, so the next thing we need to know is the diameter of the tyre.

Is it on a conveyor belt?

Dr Jekyll said:

4 3 2 1 .........

We have lift off

[Rostfritt]

glazbagun said:

It's bugging me, but was there ever a car where "spartan" was a trim level? I'm thinking maybe a Hillman Imp or suchlike, which actually boasted about its lack of frippery.

Probably wasn't a trim level, as it was a special order, by a friend of mine has a Maestro Van that's ex-BT. It has to be the most basic thing you could imagine, they didn't want to spend a penny more than they had to on giving employees nice things. I doubt it is the same these days as it is all about fleet management and considering resale values in 3-5 years.

[The Mad Monk]

RATATTAK said:

Johnspex said:

RATATTAK said:

Johnspex said:

Can anyone tell me the formula for working out how fast, in mph, a point on the tread of my tyre is travelling? Please.

Rotationally or linearly ?b

Er, not sure what that means. A point on the outer circumference of the tyre must have a speed in mph, surely. It must also be faster than one of the wheel nuts as it travels a greater distance for each revolution. If, say, the tyre circumference is 1 metreand it goes round once every second it is travelling 1m per sec. The wheel nut which part of a circle of, say, 50cm circumference will only travel 50cm per sec.

I read once about the phenomenal speed the rim of the wheels on Bloodhound SSC will travel .

Yeah you've got it, so the next thing we need to know is the diameter of the tyre.

But, but.

Let us say, for convenience that the vehicle is travelling at 100 mph. All ok, so far?

The axle of the car will also be travelling at 100 moh. Agreed?

The piece of the tread in contact with the ground will be stationary. Right?

Given these two facts, then the top of the tyre, the topmost part of the tread will be travelling at 200 mph. Or something very close to it.

QED and I rest my case.

[RATATTAK]

The Mad Monk said:

RATATTAK said:

Johnspex said:

RATATTAK said:

Johnspex said:

Can anyone tell me the formula for working out how fast, in mph, a point on the tread of my tyre is travelling? Please.

Rotationally or linearly ?b

Er, not sure what that means. A point on the outer circumference of the tyre must have a speed in mph, surely. It must also be faster than one of the wheel nuts as it travels a greater distance for each revolution. If, say, the tyre circumference is 1 metreand it goes round once every second it is travelling 1m per sec. The wheel nut which part of a circle of, say, 50cm circumference will only travel 50cm per sec.

I read once about the phenomenal speed the rim of the wheels on Bloodhound SSC will travel .

Yeah you've got it, so the next thing we need to know is the diameter of the tyre.

But, but.

Let us say, for convenience that the vehicle is travelling at 100 mph. All ok, so far?

The axle of the car will also be travelling at 100 moh. Agreed?

The piece of the tread in contact with the ground will be stationary. Right?

Given these two facts, then the top of the tyre, the topmost part of the tread will be travelling at 200 mph. Or something very close to it.

QED and I rest my case.

Correct - that's the linear bit of the equation.

[Allan L]

You may like the paradox of the locomotive and the pea:
A boy with a pea-shooter is on the platform as an express train thunders through the station at 100 m.p.h. He aims the pea-shooter at the locomotive and the pea hits the loco's smoke-box and rebounds towards the boy. The velocity of the pea changes from n f.p.s. away from the boy to N f.p.s. towards him. For that to happen, at some stage in the proceedings the pea's velocity must be zero. That can only be when the pea is in contact with the locomotive, so the locomotive must have zero velocity at some point . . .

[Ayahuasca]

Allan L said:

You may like the paradox of the locomotive and the pea:
A boy with a pea-shooter is on the platform as an express train thunders through the station at 100 m.p.h. He aims the pea-shooter at the locomotive and the pea hits the loco's smoke-box and rebounds towards the boy. The velocity of the pea changes from n f.p.s. away from the boy to N f.p.s. towards him. For that to happen, at some stage in the proceedings the pea's velocity must be zero. That can only be when the pea is in contact with the locomotive, so the locomotive must have zero velocity at some point . . .

Not a paradox. The molecules of train in contact with the pea will have zero velocity for a nanosecond. The rest of the train thunders forward as normal.

[The Moose]

Allan L said:

You may like the paradox of the locomotive and the pea:
A boy with a pea-shooter is on the platform as an express train thunders through the station at 100 m.p.h. He aims the pea-shooter at the locomotive and the pea hits the loco's smoke-box and rebounds towards the boy. The velocity of the pea changes from n f.p.s. away from the boy to N f.p.s. towards him. For that to happen, at some stage in the proceedings the pea's velocity must be zero. That can only be when the pea is in contact with the locomotive, so the locomotive must have zero velocity at some point . . .

Frozen pea?

[Lily the Pink]

Allan L said:

You may like the paradox of the locomotive and the pea:
A boy with a pea-shooter is on the platform as an express train thunders through the station at 100 m.p.h. He aims the pea-shooter at the locomotive and the pea hits the loco's smoke-box and rebounds towards the boy. The velocity of the pea changes from n f.p.s. away from the boy to N f.p.s. towards him. For that to happen, at some stage in the proceedings the pea's velocity must be zero. That can only be when the pea is in contact with the locomotive, so the locomotive must have zero velocity at some point . . .

If it rebounds towards the boy then it must have bounced off a surface which is to all intents and purpose, perpendicular to the line of fire. That being so, and assuming that the surface was the front of the smokebox, then I think the little fella has something more to worry about.

[coppernorks]

Do Freesat channels have a Watershed ?

There's a fair old smattering of a**e , s**t, and piss on those Australian gold/opal mining shows at 7pm.

[SpeckledJim]

RATATTAK said:

The Mad Monk said:

RATATTAK said:

Johnspex said:

RATATTAK said:

Johnspex said:

Can anyone tell me the formula for working out how fast, in mph, a point on the tread of my tyre is travelling? Please.

Rotationally or linearly ?b

Er, not sure what that means. A point on the outer circumference of the tyre must have a speed in mph, surely. It must also be faster than one of the wheel nuts as it travels a greater distance for each revolution. If, say, the tyre circumference is 1 metreand it goes round once every second it is travelling 1m per sec. The wheel nut which part of a circle of, say, 50cm circumference will only travel 50cm per sec.

I read once about the phenomenal speed the rim of the wheels on Bloodhound SSC will travel .

Yeah you've got it, so the next thing we need to know is the diameter of the tyre.

But, but.

Let us say, for convenience that the vehicle is travelling at 100 mph. All ok, so far?

The axle of the car will also be travelling at 100 moh. Agreed?

The piece of the tread in contact with the ground will be stationary. Right?

Given these two facts, then the top of the tyre, the topmost part of the tread will be travelling at 200 mph. Or something very close to it.

QED and I rest my case.

Correct - that's the linear bit of the equation.

This. The speed of the tread relative to the ground varies constantly between 0 and 200mph. But its speed relative to the hub (and the rest of the car) is a steady 100mph.

[Evoluzione]

ambuletz said:

Any scottish people here?

here in london Irn Bru is always very cheap/discounted compared to Coca-cola. a 2litre bottle of Irb Bru costs £1.39. compare that to coca-cola which is £2+. all the bottles and cans of Irn Bru are mega cheap.

My question is... given that Irn Bru is more popular up there than it is down here...is Irn Bru full price there? or is it one of the cheaper drinks?

Look on Tesco Scotlands website.

[Evoluzione]

Are horses mindful enough to be gentle with their teeth? Do they know that they could chomp off your finger end if it got in their mouth whilst you were feeding them and so take avoiding action?
The question arose whilst I was feeding them an apple or two on my way to work. I was taught as a kid to hold out your hand flat with the food on it, but:
A. The apple would have rolled off as Neddy went for it.
B. I didn't want hoss dribble all over me.
C. They were really keen on the apples, a huge crunch came as it chomped it in half, no way was I risking my fingers!

So I put them on the wall and they got quite good at picking them up

[kowalski655]

Evoluzione said:

ambuletz said:

Any scottish people here?

here in london Irn Bru is always very cheap/discounted compared to Coca-cola. a 2litre bottle of Irb Bru costs £1.39. compare that to coca-cola which is £2+. all the bottles and cans of Irn Bru are mega cheap.

My question is... given that Irn Bru is more popular up there than it is down here...is Irn Bru full price there? or is it one of the cheaper drinks?

Look on Tesco Scotlands website.

It varies wildly, from shop to shop & even week to week. Sometimes its £1/2L, sometimes £1.39, or £1.89, or 2 for £2. I have no way of knowing if that correlates to London pricing.Its cheaper than proper Coke due to the sugar tax, but generally similar to other low sugar stuff-certainly MaccyD's charges the same price in the drive thru.
The recent "original reipe" was something like £2/litre,silly money
Im a Londoner living in Scotland & I cant stand the stuff

[gusko]

Ayahuasca said:

What prevents an engine running backwards?

Not as in reverse, I mean as in the crankshaft moving clockwise when it should go anti-clockwise or vice versa.

Is is just the way it is spun on start-up ?

Can a normal engine be run the wrong way?

A couple of my 2 stroke snowmobiles have reverse . This is done by pressing a button on the handlebars, the revs drop down til it sounds like its stalled then fires up again running the other way. Works pretty well unless the engine is cold.

4 strokes have a gearbox, if you dont hold the brake when you select reverse the CVT seizes up and a strip and rebuild is in order.

Snowmobiles are heavy 250+kgs .. then add 30+kgs fuel ,after a bit of riding it can be up to an extra 60kgs of snow /ice stuck to it. This is why I never get an electric start machine as the battery and starter motor add extra weight that you can really notice when hauling it around the mountains. Recently a new way of starting has been available.
Its called Hotshot. Basically its a capacitor, you have to pull start the sled once at the start of the day and then the capacitor holds enough charge to fire the sled up whenever you need to throughout the day. only adds less than a kg to the sleds weight .

[P-Jay]

Clockwork Cupcake said:

glazbagun said:

It's bugging me, but was there ever a car where "spartan" was a trim level? I'm thinking maybe a Hillman Imp or suchlike, which actually boasted about its lack of frippery.

Mitsubishi Evo had a trim level that was basically "starting point for conversion to Group N Rallying". I forget what the trim level was called but it was extremely Spartan and only just road legal. However, it *was* road legal and it *was* an actual trim level / model type.

The Evos (mostly) came in 2 specs, GSR which was the 'standard' one and RS which was the one meant to be sold to Privateer Racers. There were of course a load of MR / FQ / etc special editions later on.

The differences between the GSR and RS depend on which Evo you're talking about, the original "Evo 1" RS had wind up windows and steel wheels, because what's the point of fitting electric windows if they're going to get replaced by plastic ones and road spec alloy wheels that are only going to get junked for racing wheels. It also had a rear LSD when the road one had a different kind of diff. I'm reasonably sure that early Evo RS' came with base model Lancer seats too, which would have been 'fun' on a twisty road I suppose, again, straight in the bin for most customers.

I think the RS models were only sold in Japan to punters but globally to racing teams. As the Evo, evolved the changes for the RS changed, different gearboxes, alu roof panels, different turbos etc, but they also offered more of the GSR spec as an option, so you could have a radio, electric windows and AC added if you wanted so I guess some people started to buy them as road cars.

Vauxhal made a Spartan Nova 'Club' along the same lines, it was either an SR or GSI (I forget which) with steel wheels etc.

[Clockwork Cupcake]

P-Jay said:

Clockwork Cupcake said:

glazbagun said:

It's bugging me, but was there ever a car where "spartan" was a trim level? I'm thinking maybe a Hillman Imp or suchlike, which actually boasted about its lack of frippery.

Mitsubishi Evo had a trim level that was basically "starting point for conversion to Group N Rallying". I forget what the trim level was called but it was extremely Spartan and only just road legal. However, it *was* road legal and it *was* an actual trim level / model type.

The Evos (mostly) came in 2 specs, GSR which was the 'standard' one and RS which was the one meant to be sold to Privateer Racers. There were of course a load of MR / FQ / etc special editions later on.

The differences between the GSR and RS depend on which Evo you're talking about, the original "Evo 1" RS had wind up windows and steel wheels, because what's the point of fitting electric windows if they're going to get replaced by plastic ones and road spec alloy wheels that are only going to get junked for racing wheels. It also had a rear LSD when the road one had a different kind of diff. I'm reasonably sure that early Evo RS' came with base model Lancer seats too, which would have been 'fun' on a twisty road I suppose, again, straight in the bin for most customers.

I think the RS models were only sold in Japan to punters but globally to racing teams. As the Evo, evolved the changes for the RS changed, different gearboxes, alu roof panels, different turbos etc, but they also offered more of the GSR spec as an option, so you could have a radio, electric windows and AC added if you wanted so I guess some people started to buy them as road cars.

Thanks! That is exactly what I was thinking of.



So, there's your answer then glazbagun.

[SpeckledJim]

Clockwork Cupcake said:

P-Jay said:

Clockwork Cupcake said:

glazbagun said:

It's bugging me, but was there ever a car where "spartan" was a trim level? I'm thinking maybe a Hillman Imp or suchlike, which actually boasted about its lack of frippery.

Mitsubishi Evo had a trim level that was basically "starting point for conversion to Group N Rallying". I forget what the trim level was called but it was extremely Spartan and only just road legal. However, it *was* road legal and it *was* an actual trim level / model type.

The Evos (mostly) came in 2 specs, GSR which was the 'standard' one and RS which was the one meant to be sold to Privateer Racers. There were of course a load of MR / FQ / etc special editions later on.

The differences between the GSR and RS depend on which Evo you're talking about, the original "Evo 1" RS had wind up windows and steel wheels, because what's the point of fitting electric windows if they're going to get replaced by plastic ones and road spec alloy wheels that are only going to get junked for racing wheels. It also had a rear LSD when the road one had a different kind of diff. I'm reasonably sure that early Evo RS' came with base model Lancer seats too, which would have been 'fun' on a twisty road I suppose, again, straight in the bin for most customers.

I think the RS models were only sold in Japan to punters but globally to racing teams. As the Evo, evolved the changes for the RS changed, different gearboxes, alu roof panels, different turbos etc, but they also offered more of the GSR spec as an option, so you could have a radio, electric windows and AC added if you wanted so I guess some people started to buy them as road cars.

Thanks! That is exactly what I was thinking of.



So, there's your answer then glazbagun.

Toyota GT86 was offered as the 'RC' model, on steel wheels and unpainted trim, in anticipation of them being removed straight away.