Prison Diary

[TripleS]

I'm just disappointed that NASA wasn't on the call.

Aye, that could have been 22,000 knots.

BTW, ignorance showing again here, and going slightly off the original topic:

It is said that you need a speed of about 25,000 mph to escape from Earth's gravitational pull; but if you point your rocket straight up to the sky, and keep shoving hard enough for long enough, regardless of the speed, will it not enentually escape in a straight line, rather than going round and round until you reach escape velocity?

Sorry about all this, but you'd be amazed at some of the things I don't understand......or maybe you wouldn't!

Best wishes all,
Dave.

I believe that it is actually 17,500mph to escape gravity's chains.

the rockets do (give or take a few degrees, go straight up) as they don't want to spend too much time in the ozone layer which would cook the rocket. and the fuel bill is large enough already without the need to go at an angle - which would require larger fuel tanks etc.

I read elsewhere that escape velocity is 11.2 km/sec. which seems to convert to a bit over 25,000 mph - which I suppose might be considered a fairly high speed - at least relative to our NSL.

....ananudder t'ing:

If we walk round to Australia, why don't we feel as if we're upside down and walking on a ceiling?

Best wishes all,
Dave.

[7db]

It is said that you need a speed of about 25,000 mph to escape from Earth's gravitational pull; but if you point your rocket straight up to the sky, and keep shoving hard enough for long enough, regardless of the speed, will it not enentually escape in a straight line, rather than going round and round until you reach escape velocity?

Yes. You can escape at 1mph if you keep shoving.

The issue is what happens when you stop shoving. At that point you need to have enough speed to go on to infinity rather than come crashing back down.

If you stop shoving at the surface of the Earth then the required speed is the escape velocity - 25,000mph. If you stop shoving a bit further away, then it's a bit less.

In fact rockets leaving Earth get to about 18,000 mph peak speed.

[7db]

I'm just disappointed that NASA wasn't on the call.

Aye, that could have been 22,000 knots.

BTW, ignorance showing again here, and going slightly off the original topic:

It is said that you need a speed of about 25,000 mph to escape from Earth's gravitational pull; but if you point your rocket straight up to the sky, and keep shoving hard enough for long enough, regardless of the speed, will it not enentually escape in a straight line, rather than going round and round until you reach escape velocity?

Sorry about all this, but you'd be amazed at some of the things I don't understand......or maybe you wouldn't!

Best wishes all,
Dave.

I believe that it is actually 17,500mph to escape gravity's chains.

the rockets do (give or take a few degrees, go straight up) as they don't want to spend too much time in the ozone layer which would cook the rocket. and the fuel bill is large enough already without the need to go at an angle - which would require larger fuel tanks etc.

I read elsewhere that escape velocity is 11.2 km/sec. which seems to convert to a bit over 25,000 mph - which I suppose might be considered a fairly high speed - at least relative to our NSL.

....ananudder t'ing:

If we walk round to Australia, why don't we feel as if we're upside down and walking on a ceiling?

Best wishes all,
Dave.

Best wishes all,
Dave.

Cos the ceilings are upside down there too.

[TripleS]

If we walk round to Australia, why don't we feel as if we're upside down and walking on a ceiling?

Best wishes all,
Dave.

Cos the ceilings are upside down there too.

Ooooh, thanks. Coo, I wish I wuz clever and understood t'ings like dat.

Best wishes all,
Dave.

[Red Herring]

I agree with VON on this one,

What we have here is a terminology conflict between the words high, and fast.

I wouldn't consider 70mph high speed. If we take the speed range of all road going vehicles, it will vary from as low as under 10 mph for invalid buggies, up to 200mph + for super cars and bikes. In that context 70mph is not high. What we are talking about here is a numerical scale where 70 sits approximately one third of the way up. It is therefore not high. On the other hand it could be considered fast, ex, "He was driving fast, but not speeding". This statement does not mention numerical speed, only that the driver was not considered to be breaking the speed limit, but driving fast within the legal constraints placed upon him. And the folowing statement, "His speed was too high for the circumstances". Niether of these statements tells us that the driver was travelling at high speed, only that the driver was travelling at a speed that was too fast or too high for the circumstances. He may have been travelling at 25mph past a school, between double parked cars at school leaving time, with parents collecting chidren. Not high speed, but way too fast.

The example of the pedestrian walking at 5mph would be a fast walking pace, but not a fast running pace, and certainly not high speed.

Nigel ADI
IAM trainee observer

Given that it was probably me that started this "discussion" with Von over what is and what isn't high speed it's probably fair that at this point I concede that I rather like the above explanation. In truth I was probably a little guilty of playing devils advocate over this as in my book high speed has always been something over 100mph, it's just a bit hard to discuss such speeds without the righteous brigade jumping all over you. So in short Von, you were right all along! Still doesn't change my view on what happened to the blogger though.

[martine]

...the rockets do (give or take a few degrees, go straight up)...

Oh no they don't! Almost immediately from lift-off they start leaning which carries on increasing until they are, of course, horizontal to the ground (at orbit). Listen to the height/speed/distance readouts on the commentary when a shuttle lifts off. Within 50 secs. a shuttle is 2-3 miles high but 7+ miles 'downrange' (and already supersonic).
Here's a good example:
http://www.nasa.gov/multimedia/nasatv/on_demand_video.html?param=http://anon.nasa-global.edgesuite.net/anon.nasa-global/ksc/ksc_020708_sts122_launch.asx&_id=115121&_title=Lift%20Off%21&_tnimage=210579main_ksc_020708_sts122_launch-t.gif

...as they don't want to spend too much time in the ozone layer which would cook the rocket.

Nah...the ozone layer isn't hot, it just has a higher concentration of ozone than the 'normal' atmosphere we breath. It's far hotter in space (and cooler!) than anything in the atmosphere.

[7db]

I think Apollo launched more vertically than that, but at best 45 degrees. Best not to hit mach 5 over land, of course.

I was looking for evidence and found this video of launch. It's mesmerising.

http://centripetalnotion.com/2007/11/18/14:01:50/

[spurs-442]

...the rockets do (give or take a few degrees, go straight up)...

Oh no they don't! Almost immediately from lift-off they start leaning which carries on increasing until they are, of course, horizontal to the ground (at orbit). Listen to the height/speed/distance readouts on the commentary when a shuttle lifts off. Within 50 secs. a shuttle is 2-3 miles high but 7+ miles 'downrange' (and already supersonic).
Here's a good example:
http://www.nasa.gov/multimedia/nasatv/on_demand_video.html?param=http://anon.nasa-global.edgesuite.net/anon.nasa-global/ksc/ksc_020708_sts122_launch.asx&_id=115121&_title=Lift%20Off%21&_tnimage=210579main_ksc_020708_sts122_launch-t.gif

...as they don't want to spend too much time in the ozone layer which would cook the rocket.

Nah...the ozone layer isn't hot, it just has a higher concentration of ozone than the 'normal' atmosphere we breath. It's far hotter in space (and cooler!) than anything in the atmosphere.

yep, sorry, hold my hands up - please send all blame to my old science teacher . as for the cooking of the rocket, i meant that the radiation is quite severe and i remember somewhere that the astronauts (sp) can't spend too long in the outer stratosphere otherwise the rocket breaks up or the raditation causes major problems.

please feel free to correct me if i'm wrong

[spurs-442]

I think Apollo launched more vertically than that, but at best 45 degrees. Best not to hit mach 5 over land, of course.

I was looking for evidence and found this video of launch. It's mesmerising.

http://centripetalnotion.com/2007/11/18/14:01:50/

that is pretty amazing i must say. what on earth was the blue smoke coming down afterwards? cool effect on the pillars with the flame running down.

[TripleS]

I think Apollo launched more vertically than that, but at best 45 degrees. Best not to hit mach 5 over land, of course.

I was looking for evidence and found this video of launch. It's mesmerising.

http://centripetalnotion.com/2007/11/18/14:01:50/

that is pretty amazing i must say. what on earth was the blue smoke coming down afterwards?

Either they forgot to push the choke in, or it's running a bit rich. Obviously it needs the carburetters tuning, otherwise the fuel consumption is going to be a bit on the high side - and they'll lose some performance.

Best wishes all,
Dave.

[martine]

...as for the cooking of the rocket, i meant that the radiation is quite severe and i remember somewhere that the astronauts (sp) can't spend too long in the outer stratosphere otherwise the rocket breaks up or the raditation causes major problems.

please feel free to correct me if i'm wrong

OK...you're wrong!
The radiation problem is worse when they are outside the protective effect of the atmosphere (in orbit and beyond). There is concern that all sorts of nasties zap the electronics and astronauts...never really been resolved for loooong missions (like Mars) but reassuringly there seem to be plenty of old astronauts knocking around without ill effects.

[7db]

Worth reading the transcript of the Apollo 12 launch as well. All fine up to 36s when they are hit by lightening and all the warning lights go on at once.

Not what you want when you're sitting on a big lox bomb.

[Daaave]

Well I'm glad this link has caused plenty of debate, although you lot have succeeded in taking it waaaay off topic

My own personal view is that I totally agree with the view of his actions by the judge and I think the driver got what he deserved. I would agree with others in that we all need to think very carefully about how you overtake anyone in order to cause as little offence as possible, not just because of what could potentially be said in court, but if people do end up flashing their lights at you they must have been annoyed at some aspect - whether we think they're being unreasonable or not. I would rather make reasonable progress silently, than good progress at the expense of pissing off another driver.

Looking at this blog makes me want to get my arse in gear and do more track days to allow me the freedom to explore the car in a safe(er) environment.

Oh, and I agree with Von's definition. 50 in a 60 may be inappropriate, but isn't a high speed.

[Gareth]

Being late to the party I thought I'd add my view

I think high speed is something that is unusual for the majority of the population taking part in the specific activity. For driving cars, I would say high speed is when you need to consider the effects of undulations in the road surface on an otherwise decent B-road, or be careful of wind effects when passing under motorway bridges.

The circumstances that some seem to ascribe to high speed I would think of as being inappropriately fast.