Things you always wanted to know the answer to [Vol. 3]
Discussion
The stone is flicked upwards and it is the speed of your vehicle that does the damage. A bit like throwing a tennis ball in the air and then whacking it with a racket. The stone is stationary relative to its surrounds; although you're doing 80mph, relative to the vehicle in front you're stationary. You can throw a stone from your car to the next, as both cars AND stone, relative to each other are stationary (the stone has momentum from already travelling at 80mph) but if you miss, and it hits a bystander, the stone is travelling at 80mph already and thus the bystander is killed.
oceanview said:
Say you're driving along at 70-80mph on the motorway and a stone is "flicked" by a vehicle in front and hits your windscreen- has it actually been propelled back towards you or is flicked more or less upwards and you hit it due to your approaching speed??
Assuming it's flicked from the a road, the of the tyre that flicks it up is doing zero mph, so you're driving into a slow moving stone.Wiccan of Darkness said:
The stone is flicked upwards and it is the speed of your vehicle that does the damage. A bit like throwing a tennis ball in the air and then whacking it with a racket. The stone is stationary relative to its surrounds; although you're doing 80mph, relative to the vehicle in front you're stationary. You can throw a stone from your car to the next, as both cars AND stone, relative to each other are stationary (the stone has momentum from already travelling at 80mph) but if you miss, and it hits a bystander, the stone is travelling at 80mph already and thus the bystander is killed.
incorrect, the stone is propelled backwards, see accelerating on gravel.JustinF said:
incorrect, the stone is propelled backwards, see accelerating on gravel.
But that's because of wheelspin.You're not wheelspinning in fifth in the second lane of a dual carriageway when you flick a stone up.
eta - unless you're an absolute hero
Edited by talksthetorque on Sunday 11th June 10:53
glazbagun said:
How did they make the first rulers, micrometers, worm gears and dividing heads, etc? Or any kind of high precision tool when there was nothing so precise that existed before it?
In one of those case, I think it was Whitworth(?) who devised a machine that took a hand-cut screw thread and, using it as a template, cut an even more precise, or at least more regular, thread.talksthetorque said:
JustinF said:
incorrect, the stone is propelled backwards, see accelerating on gravel.
But that's because of wheelspin.You're not wheelspinning in fifth in the second lane of a dual carriageway when you flick a stone up.
eta - unless you're an absolute hero
Edited by talksthetorque on Sunday 11th June 10:53
kowalski655 said:
talksthetorque said:
JustinF said:
incorrect, the stone is propelled backwards, see accelerating on gravel.
But that's because of wheelspin.You're not wheelspinning in fifth in the second lane of a dual carriageway when you flick a stone up.
eta - unless you're an absolute hero
Edited by talksthetorque on Sunday 11th June 10:53
MartG said:
kowalski655 said:
talksthetorque said:
JustinF said:
incorrect, the stone is propelled backwards, see accelerating on gravel.
But that's because of wheelspin.You're not wheelspinning in fifth in the second lane of a dual carriageway when you flick a stone up.
eta - unless you're an absolute hero
Edited by talksthetorque on Sunday 11th June 10:53
glazbagun said:
How did they make the first rulers, micrometers, worm gears and dividing heads, etc? Or any kind of high precision tool when there was nothing so precise that existed before it?
Mathematics. There was no way of creating a perfect right angle until Pythagoras. Then a 3, 4, 5 triangle created that first right angle. Compasses and calipers came next, and using a combination, more accurate division tools came about. Got a right angle, but no 45 degree angle, use perpendicular bisection.True accuracy only came about with standardised weights and measures in the 18th century, even though the romans got there first.
Standardised weights and measures oddly enough was my number 2 most important invention or discovery in history, for the advancement of science and technology (number 1 was glass)
Wiccan of Darkness said:
Mathematics. There was no way of creating a perfect right angle until Pythagoras. Then a 3, 4, 5 triangle created that first right angle. Compasses and calipers came next, and using a combination, more accurate division tools came about. Got a right angle, but no 45 degree angle, use perpendicular bisection.
True accuracy only came about with standardised weights and measures in the 18th century, even though the romans got there first.
Standardised weights and measures oddly enough was my number 2 most important invention or discovery in history, for the advancement of science and technology (number 1 was glass)
The Egyptians were doing some pretty accurate measuring 3000 years before the Roman Empire. We just don't really know how they did things, i.e. What methodology they used. True accuracy only came about with standardised weights and measures in the 18th century, even though the romans got there first.
Standardised weights and measures oddly enough was my number 2 most important invention or discovery in history, for the advancement of science and technology (number 1 was glass)
Halmyre said:
glazbagun said:
How did they make the first rulers, micrometers, worm gears and dividing heads, etc? Or any kind of high precision tool when there was nothing so precise that existed before it?
In one of those case, I think it was Whitworth(?) who devised a machine that took a hand-cut screw thread and, using it as a template, cut an even more precise, or at least more regular, thread.How many people are alive today that would definetly have killed themselves overdosing on paracetamol thanks to the limiting of only two boxes per transaction at a supermarket?
So we had two boxes today and some neurofen. Got refused to buy them. But the guy actually said we could go to separate tills. I assume people killing themselves woth overdoses are too upset to think about this though.....
So we had two boxes today and some neurofen. Got refused to buy them. But the guy actually said we could go to separate tills. I assume people killing themselves woth overdoses are too upset to think about this though.....
TTmonkey said:
How many people are alive today that would definetly have killed themselves overdosing on paracetamol thanks to the limiting of only two boxes per transaction at a supermarket?
So we had two boxes today and some neurofen. Got refused to buy them. But the guy actually said we could go to separate tills. I assume people killing themselves woth overdoses are too upset to think about this though.....
I had an argument with a cashier about this, as I said, if i was suicidal, i could go buy bleach or stanley blades. or i could just go to each till or lots of different shops.So we had two boxes today and some neurofen. Got refused to buy them. But the guy actually said we could go to separate tills. I assume people killing themselves woth overdoses are too upset to think about this though.....
turns out is not to prevent intentional deaths/overdoses, it's the accidental ones. if you go buy two packets and take the lot, it's just under the dose to kill you. and if you go to a pharmacy you can get more but it will be explained to you.
Wiccan of Darkness said:
Mathematics. There was no way of creating a perfect right angle until Pythagoras. Then a 3, 4, 5 triangle created that first right angle. Compasses and calipers came next, and using a combination, more accurate division tools came about. Got a right angle, but no 45 degree angle, use perpendicular bisection.
True accuracy only came about with standardised weights and measures in the 18th century, even though the romans got there first.
Standardised weights and measures oddly enough was my number 2 most important invention or discovery in history, for the advancement of science and technology (number 1 was glass)
But how did they, for example, make the first Metre stick? It's fine knowing that a Metre is one ten-millionth of the distance from the equator to the North Pole and that a centimetre is a hundredth of that, but even if you converted it from imperial you'd still at some point need to make a standard measuring stick for the first time. True accuracy only came about with standardised weights and measures in the 18th century, even though the romans got there first.
Standardised weights and measures oddly enough was my number 2 most important invention or discovery in history, for the advancement of science and technology (number 1 was glass)
I'm familiar with some rudimentary things which are pretty cool. I know that you can hand scrape a surface perfectly (or as perfect as manually possible) flat if you simultaneously make three of them and rub the uneven surfaces together to reveal high spots.
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