Gorilla glass is stated to be approximately 6.8 on the Mohs scale which puts it just under quartz (7.0) in terms of hardness. Which means that only items in your pockets harder than 6.8 Mohs could scratch the surface. Keys are normally cut from brass. Brass is only 5.5-6.0 on the Mohs scale. Tool steel (like files, chisels and the like) can be hardened to 7 or higher on the Mohs scale, which would scratch Gorilla glass. I can, and have, run the tip of my house key back and forth across the face of my iPhone countless times, pressing fairly hard - and it has never scratched. I carry my iPhone in my pocket with keys and pens all the time and have not had a single scratch. Whatever it was in your pocket (pocket knife, emery board, gravel, diamond stylus) besides your keys was what scratched it - not your keys.
And no, in real world application Gorilla glass is not "extremely fragile". I have cracked plastic screens at less than 3 feet dropping, I have shattered crystal glasses, lightbulbs and eggs at that height, but not my iPhone. If you are drop prone, any device should be protected by a case. It sounds like your iPhone struck on one of the corners without protection, which of course concentrates the force into a very small contact point and would result in the screen shattering due to the forces passing through the material. Or it is possible that there was a flaw in the material not caught in QA coming off the production line. I have taken the back panel of an iPhone 4 and bent it double before it snapped in two.
Gravel is everywhere and extremely small particles. It is those that probably was between the keys and the iphone glass.... I have dropped my iphone 3G just once in my life and it landed on its face on some large rhinestone gravel on a building site. It broke right away (dropped from pocket when i got out of the car about 1m)
You have zero faith in the mainstream media, but you'll accept Wikipedia as a source? ...
You've been listening to the "mainstream media" too much yourself if you think Wikipedia is a bad source. All examinations of it have shown that Wikipedia is far more accurate than most academic sources.
Even the worst academic source is going to be light years more accurate than the "mainstream media" which is (technically) part of the entertainment industry and not generally accurate at all.
Wikipedia is a great source and is rarely substantially wrong at all, on any topic. Those are the facts.
That was my experience until one day I found a significant scratch on the front of my IP4. Never did figure out what it might have come into contact with to do that. Unless it was my BlackBerry...
The shell rings that hold the brass keys together can sometimes do it or one of the many fobs and other junk that people hang on their keys. Also a single grain of sand stuck in the keys or your pocket will do it.
As long as you keep the iPhone in a pocket by itself and don't get sand or dirt in that pocket, it will never scratch.
Interesting; what field did you study? As a ChE, our usage of pounds was almost always pounds-mass, so i tend to assume that.
I'm in the aerospace industry, and we, on a daily basis use pound-mass and pound-force. We rarely ever say pound-mass and pound-force. Just pounds for everything. Everyone basically understands what we mean by the context of the conversation. Every once in awhile, someone will trot out a slug and throws everyone off as no one has a good feel for how heavy a slug is.
And those SI diehards, they suck! Pascals? Newtons? No idea what they are talking about.
I'm in the aerospace industry, and we, on a daily basis use pound-mass and pound-force. We rarely ever say pound-mass and pound-force. Just pounds for everything. Everyone basically understands what we mean by the context of the conversation. Every once in awhile, someone will trot out a slug and throws everyone off as no one has a good feel for how heavy a slug is.
And those SI diehards, they suck! Pascals? Newtons? No idea what they are talking about.
According to Wikipedia, slugs rarely exceed about 4 oz.
I wonder how much Corning has profited by Apple's getting them to dig up this 50yo tech? Hasn't Apple also helped other companies pull shelved tech into production they thought had no potential customers?
Well, you could argue that Apple *revived* tablet technology and, in the process, substantially enlarged the market for medium size touchscreens (while not 50 yrs old, they have been around for a while), allowing Samsung and others to profit.
Quote:
Originally Posted by ash471
Exactly. And that is also why Corning is catering to the "PC crowd" by saying they will be the first laptops to get Gorilla Glass. I'm sure the reference to laptops isn't a coincidence. This probably has to do with the fact that new Apple laptops are scheduled to ship until after the PC laptops. My guess is the new iPad will be the first product to have Gorilla Glass 2. However, it wouldn't make any sense for Corning to tout that at CES.
HP just announced the Envy 14 *ultrabook*, with gorilla glass used for the screen, the back of the screen (i.e. the lid of the computer) and the entire palm rest area, including the touchpad. Not sure if this is GG 1 or 2 (kind of hilarious when materials have version numbers; wonder if there will be update downloads for GG2.1).
You raise an interesting point. Can a material with a hardens of 6 scratch a material with a hardness of 7? I had to pause and think about this. However, I think it can.
And you'd be wrong.
By definition, an item will NOT scratch something above it on the Mohs scale.
A mineral with a given hardness rating will scratch other minerals of the same hardness and all samples with lower hardness ratings.
This is complicated slightly by the fact that hardness can vary with the direction that you are scratching. For example, a mineral might be a 6.5 in one direction, but a 7.0 in another direction. In addition, most materials have impurities, so hardness can vary throughout a sample.
Quote:
Originally Posted by ash471
It depends on several different factors like the geometry of the contact surfaces and the force applied. An easy example that shows you don't have to have a harder material to etch a surface is the fact that steel can be cut with a high pressure water stream. Water has a hardness of 0 on the mohs scale.
Wrong there, too.
First water does not have a Mohs hardness. Since it's impossible to 'scratch' water, Mohs hardness is meaningless for a liquid.
Second, water jet cutting does not work by 'scratching' the surface, so it is not really relevant to Mohs hardness. And for cutting steel, an abrasive is usually added, anyway.
Second, water jet cutting does not work by 'scratching' the surface, so it is not really relevant to Mohs hardness. And for cutting steel, an abrasive is usually added, anyway.
That's true - abrasives are often added, which adds another hardness-dependent mechanism - erosion.
I'm in the aerospace industry, and we, on a daily basis use pound-mass and pound-force. We rarely ever say pound-mass and pound-force. Just pounds for everything. Everyone basically understands what we mean by the context of the conversation. Every once in awhile, someone will trot out a slug and throws everyone off as no one has a good feel for how heavy a slug is.
And those SI diehards, they suck! Pascals? Newtons? No idea what they are talking about.
Your first paragraph pretty much explains why the SI system was necessary. Boy, does that bring back memories of first and second year engineering! Multiply by 32. No no, divide!
Interesting; what field did you study? As a ChE, our usage of pounds was almost always pounds-mass, so i tend to assume that.
Sorry, but real scientists make fun of chemical engineers because everything is an approximation and they are rarely all that rigorous.
Besides, for a chemical engineer, work is generally done at ground level, so the two are equivalent.
Quote:
Originally Posted by muppetry
I'm sure that your qualifications are excellent, but are you quite sure that you want to use your graduate class experience as the definitive ruling on this? I'm curious - since mass is one of the fundamental quantities in physics - how come you rarely needed it?
Because, like most scientists, we use Metric?
Quote:
Originally Posted by muppetry
OK - I guess we simply disagree on this point. When I review journal articles for publication, if SI, though preferred, is not used, I require lbf for force. I am unaware of any publishing format guidance that follows the opposite convention that you have used, but perhaps you can point to some? Alternatively, do you have a better source than Wikipedia to support your view on this?
Anyway - we are digging in the weeds of archaic unit systems that should have been abandoned years ago in favor of SI, and we are only arguing about notation conventions, rather than substantive issues of meaning or use, and we are getting rather off topic.
I already provided it. Look up ANY definition of 'weight' The definition is invariably "the force an object applies due to gravity." or equivalent. Weight is always a force.
This is a fun discussion, but we may be boring everyone else on the thread. Well never mind. I asked that question because of your original comment; "Pound was universally used as a FORCE and if we wanted to use it as a mass (although there was rarely any reason to do so), we would use 'pound-mass'". I wondered why you were rarely using mass when using pound as a force. I may have misunderstood your comment - you meant rarely using those units at maybe.
Quote:
Originally Posted by jragosta
I already provided it. Look up ANY definition of 'weight' The definition is invariably "the force an object applies due to gravity." or equivalent. Weight is always a force.
Actually you didn't supply any reference or source at all - just asserted that WP was wrong. Weight is indeed a force, but that does not, in any way, constrain the definition of the pound. Its commonplace use is undoubtedly to describe weight, but I thought we were discussing its scientific use.
See - I lied when I said we had stopped arguing...
You have zero faith in the mainstream media, but you'll accept Wikipedia as a source?
Pound is traditionally defined as a measure of weight. Weight is force, not mass (That is, it is the downward force on an object caused by gravity). The confusion is caused by the fact that normal experience is that all of us experience 1 G acceleration due to gravity, so force and mass are considered equivalent when it comes to 'weight'.
I can't believe people are debating about this for 10 posts... You are exchanging mass for weight. Most people tell that pound is a measure of weight while in reality it's a measure of mass. Mass can be expressed in pounds for the british and kilograms (not grams) in international units. Weight is a force and all forces are measured in Newtons. On Earth, the weight of 1 kilogram (Kg) is 9,8 Newtons (N).
That said, the bending test is actually important since the more a material can bend, the more it's supposed to absorb the energy of an impact by...bending and vibrating.
And apparently, iPhones haven't been using Gorilla glass since 4.
I can't believe people are debating about this for 10 posts... You are exchanging mass for weight. Most people tell that pound is a measure of weight while in reality it's a measure of mass. Mass can be expressed in pounds for the british and kilograms (not grams) in international units. Weight is a force and all forces are measured in Newtons. On Earth, the weight of 1 kilogram (Kg) is 9,8 Newtons (N).
It's because pounds have been used in several scientific and engineering systems of units and as an informal unit for a long time, and so all of the opinions have some claim to be correct. We are actually debating current usage and notation (I think), and that is where we don't all agree. I apologize for the distraction from the topic at hand.
I can't believe people are debating about this for 10 posts... You are exchanging mass for weight. Most people tell that pound is a measure of weight while in reality it's a measure of mass. Mass can be expressed in pounds for the british and kilograms (not grams) in international units. Weight is a force and all forces are measured in Newtons. On Earth, the weight of 1 kilogram (Kg) is 9,8 Newtons (N).
That said, the bending test is actually important since the more a material can bend, the more it's supposed to absorb the energy of an impact by...bending and vibrating.
And apparently, iPhones haven't been using Gorilla glass since 4.
There have been rumors that Apple has turned to Asahi instead. But like many Apple rumors, this is unsubstantiated.
Corning itself issued a profits warning a couple of months ago, attributing the problem in part to a major Korean customer who first strong-armed Corning into substantial price reduction and then reneged on a substantial order. This could be Samsung cutting its losses on its tablet business, or Samsung switching to a different supplier on orders from Apple.
Again, no direct evidence linking Apple and Corning, or breaking links between them.
There have been rumors that GG is used in Apple notebooks. I don't think these have been substantiated either.
It's because pounds have been used in several scientific and engineering systems of units and as an informal unit for a long time, and so all of the opinions have some claim to be correct. We are actually debating current usage and notation (I think), and that is where we don't all agree. I apologize for the distraction from the topic at hand.
Well about that I wouldn't know since I studied in France so it was all easy for us, no conversions and fortunately no pounds!
I don't even know how much a pound is and I don't want to know!:P
I usually tend to understand pound-mass when I say pound, much like majjo has pointed out. The reason for this is simple: when I buy a pound of apples at the market, I expect 453.59237 grams of apples, not 4.44822162 newtons of apples. How that is being measured is immaterial to me, as long as I'm not getting ripped off.
Ohhh, but you are actually getting that much in pounds, yes the force of the Apples! The number derives strictly from the force the fully laden basket of Apples is applying to the scale. The force or weight weight of your apples is intrinsically the local force of Earth gravity and Apple gravity mutually attracting each other.
The mass of the Apples is their physical property independent of the effects of a local gravity well. Pounds or lbs is a force that intrinsically incorporates the gravitational attraction of the earth. Non-Earth vertical force scales can be calibrated to read properly in the vertical and then the force in pounds can be measured in directions other than Earth vertical.
So yes, pounds is a unit of force, a derived unit of force to take a quasi SI view of it, but nonetheless a unit of force.
And just the same pounds is a unit of mass, a sloppy nasty one, but yes a unit of mass as has been argued at length in previous posts.
Bottom line is the usage is very context dependent and that potential ball of confusion was a reason things like the SI system were developed in the first place.
Comments
Gorilla glass is stated to be approximately 6.8 on the Mohs scale which puts it just under quartz (7.0) in terms of hardness. Which means that only items in your pockets harder than 6.8 Mohs could scratch the surface. Keys are normally cut from brass. Brass is only 5.5-6.0 on the Mohs scale. Tool steel (like files, chisels and the like) can be hardened to 7 or higher on the Mohs scale, which would scratch Gorilla glass. I can, and have, run the tip of my house key back and forth across the face of my iPhone countless times, pressing fairly hard - and it has never scratched. I carry my iPhone in my pocket with keys and pens all the time and have not had a single scratch. Whatever it was in your pocket (pocket knife, emery board, gravel, diamond stylus) besides your keys was what scratched it - not your keys.
And no, in real world application Gorilla glass is not "extremely fragile". I have cracked plastic screens at less than 3 feet dropping, I have shattered crystal glasses, lightbulbs and eggs at that height, but not my iPhone. If you are drop prone, any device should be protected by a case. It sounds like your iPhone struck on one of the corners without protection, which of course concentrates the force into a very small contact point and would result in the screen shattering due to the forces passing through the material. Or it is possible that there was a flaw in the material not caught in QA coming off the production line. I have taken the back panel of an iPhone 4 and bent it double before it snapped in two.
Gravel is everywhere and extremely small particles. It is those that probably was between the keys and the iphone glass.... I have dropped my iphone 3G just once in my life and it landed on its face on some large rhinestone gravel on a building site. It broke right away (dropped from pocket when i got out of the car about 1m)
... Now with iphone 4 and 4S its about 70% easier to crack the screen glass or the back glass than 3G/3GS was because of the design...
Total BS.
This is what people mean when they talk about completely made up statistics.
You have zero faith in the mainstream media, but you'll accept Wikipedia as a source?
You've been listening to the "mainstream media" too much yourself if you think Wikipedia is a bad source. All examinations of it have shown that Wikipedia is far more accurate than most academic sources.
Even the worst academic source is going to be light years more accurate than the "mainstream media" which is (technically) part of the entertainment industry and not generally accurate at all.
Wikipedia is a great source and is rarely substantially wrong at all, on any topic. Those are the facts.
That was my experience until one day I found a significant scratch on the front of my IP4. Never did figure out what it might have come into contact with to do that. Unless it was my BlackBerry...
The shell rings that hold the brass keys together can sometimes do it or one of the many fobs and other junk that people hang on their keys. Also a single grain of sand stuck in the keys or your pocket will do it.
As long as you keep the iPhone in a pocket by itself and don't get sand or dirt in that pocket, it will never scratch.
What school did you attend? Pounds are units of force. The english unit of mass is the slug.
slug *or* pound can be used for mass when not using SI units, but let's face it ...
... everyone uses SI units and the Imperial junk is just a confusing mess that's best forgotten and ignored.
... everyone uses SI units...
I wish that were so. Not in the US.
?Imperial junk is just a confusing mess that's best forgotten and ignored.
Because "Give them a centimeter and they'll take a kilometer" has such a nice ring to it.
Interesting; what field did you study? As a ChE, our usage of pounds was almost always pounds-mass, so i tend to assume that.
I'm in the aerospace industry, and we, on a daily basis use pound-mass and pound-force. We rarely ever say pound-mass and pound-force. Just pounds for everything. Everyone basically understands what we mean by the context of the conversation. Every once in awhile, someone will trot out a slug and throws everyone off as no one has a good feel for how heavy a slug is.
And those SI diehards, they suck!
I'm in the aerospace industry, and we, on a daily basis use pound-mass and pound-force. We rarely ever say pound-mass and pound-force. Just pounds for everything. Everyone basically understands what we mean by the context of the conversation. Every once in awhile, someone will trot out a slug and throws everyone off as no one has a good feel for how heavy a slug is.
And those SI diehards, they suck!
According to Wikipedia, slugs rarely exceed about 4 oz.
Sure, they are doing what Intel does It's smart.
I wonder how much Corning has profited by Apple's getting them to dig up this 50yo tech? Hasn't Apple also helped other companies pull shelved tech into production they thought had no potential customers?
Well, you could argue that Apple *revived* tablet technology and, in the process, substantially enlarged the market for medium size touchscreens (while not 50 yrs old, they have been around for a while), allowing Samsung and others to profit.
Exactly. And that is also why Corning is catering to the "PC crowd" by saying they will be the first laptops to get Gorilla Glass. I'm sure the reference to laptops isn't a coincidence. This probably has to do with the fact that new Apple laptops are scheduled to ship until after the PC laptops. My guess is the new iPad will be the first product to have Gorilla Glass 2. However, it wouldn't make any sense for Corning to tout that at CES.
HP just announced the Envy 14 *ultrabook*, with gorilla glass used for the screen, the back of the screen (i.e. the lid of the computer) and the entire palm rest area, including the touchpad. Not sure if this is GG 1 or 2 (kind of hilarious when materials have version numbers; wonder if there will be update downloads for GG2.1).
You raise an interesting point. Can a material with a hardens of 6 scratch a material with a hardness of 7? I had to pause and think about this. However, I think it can.
And you'd be wrong.
By definition, an item will NOT scratch something above it on the Mohs scale.
http://chemistry.about.com/od/geoche.../mohsscale.htm
A mineral with a given hardness rating will scratch other minerals of the same hardness and all samples with lower hardness ratings.
This is complicated slightly by the fact that hardness can vary with the direction that you are scratching. For example, a mineral might be a 6.5 in one direction, but a 7.0 in another direction. In addition, most materials have impurities, so hardness can vary throughout a sample.
It depends on several different factors like the geometry of the contact surfaces and the force applied. An easy example that shows you don't have to have a harder material to etch a surface is the fact that steel can be cut with a high pressure water stream. Water has a hardness of 0 on the mohs scale.
Wrong there, too.
First water does not have a Mohs hardness. Since it's impossible to 'scratch' water, Mohs hardness is meaningless for a liquid.
Second, water jet cutting does not work by 'scratching' the surface, so it is not really relevant to Mohs hardness. And for cutting steel, an abrasive is usually added, anyway.
Second, water jet cutting does not work by 'scratching' the surface, so it is not really relevant to Mohs hardness. And for cutting steel, an abrasive is usually added, anyway.
That's true - abrasives are often added, which adds another hardness-dependent mechanism - erosion.
I'm in the aerospace industry, and we, on a daily basis use pound-mass and pound-force. We rarely ever say pound-mass and pound-force. Just pounds for everything. Everyone basically understands what we mean by the context of the conversation. Every once in awhile, someone will trot out a slug and throws everyone off as no one has a good feel for how heavy a slug is.
And those SI diehards, they suck!
Your first paragraph pretty much explains why the SI system was necessary.
Interesting; what field did you study? As a ChE, our usage of pounds was almost always pounds-mass, so i tend to assume that.
Sorry, but real scientists make fun of chemical engineers because everything is an approximation and they are rarely all that rigorous.
Besides, for a chemical engineer, work is generally done at ground level, so the two are equivalent.
I'm sure that your qualifications are excellent, but are you quite sure that you want to use your graduate class experience as the definitive ruling on this? I'm curious - since mass is one of the fundamental quantities in physics - how come you rarely needed it?
Because, like most scientists, we use Metric?
OK - I guess we simply disagree on this point. When I review journal articles for publication, if SI, though preferred, is not used, I require lbf for force. I am unaware of any publishing format guidance that follows the opposite convention that you have used, but perhaps you can point to some? Alternatively, do you have a better source than Wikipedia to support your view on this?
Anyway - we are digging in the weeds of archaic unit systems that should have been abandoned years ago in favor of SI, and we are only arguing about notation conventions, rather than substantive issues of meaning or use, and we are getting rather off topic.
I already provided it. Look up ANY definition of 'weight' The definition is invariably "the force an object applies due to gravity." or equivalent. Weight is always a force.
Because, like most scientists, we use Metric?
This is a fun discussion, but we may be boring everyone else on the thread. Well never mind. I asked that question because of your original comment; "Pound was universally used as a FORCE and if we wanted to use it as a mass (although there was rarely any reason to do so), we would use 'pound-mass'". I wondered why you were rarely using mass when using pound as a force. I may have misunderstood your comment - you meant rarely using those units at maybe.
I already provided it. Look up ANY definition of 'weight' The definition is invariably "the force an object applies due to gravity." or equivalent. Weight is always a force.
Actually you didn't supply any reference or source at all - just asserted that WP was wrong. Weight is indeed a force, but that does not, in any way, constrain the definition of the pound. Its commonplace use is undoubtedly to describe weight, but I thought we were discussing its scientific use.
See - I lied when I said we had stopped arguing...
You have zero faith in the mainstream media, but you'll accept Wikipedia as a source?
Pound is traditionally defined as a measure of weight. Weight is force, not mass (That is, it is the downward force on an object caused by gravity). The confusion is caused by the fact that normal experience is that all of us experience 1 G acceleration due to gravity, so force and mass are considered equivalent when it comes to 'weight'.
I can't believe people are debating about this for 10 posts... You are exchanging mass for weight. Most people tell that pound is a measure of weight while in reality it's a measure of mass. Mass can be expressed in pounds for the british and kilograms (not grams) in international units. Weight is a force and all forces are measured in Newtons. On Earth, the weight of 1 kilogram (Kg) is 9,8 Newtons (N).
That said, the bending test is actually important since the more a material can bend, the more it's supposed to absorb the energy of an impact by...bending and vibrating.
And apparently, iPhones haven't been using Gorilla glass since 4.
I can't believe people are debating about this for 10 posts... You are exchanging mass for weight. Most people tell that pound is a measure of weight while in reality it's a measure of mass. Mass can be expressed in pounds for the british and kilograms (not grams) in international units. Weight is a force and all forces are measured in Newtons. On Earth, the weight of 1 kilogram (Kg) is 9,8 Newtons (N).
It's because pounds have been used in several scientific and engineering systems of units and as an informal unit for a long time, and so all of the opinions have some claim to be correct. We are actually debating current usage and notation (I think), and that is where we don't all agree. I apologize for the distraction from the topic at hand.
I can't believe people are debating about this for 10 posts... You are exchanging mass for weight. Most people tell that pound is a measure of weight while in reality it's a measure of mass. Mass can be expressed in pounds for the british and kilograms (not grams) in international units. Weight is a force and all forces are measured in Newtons. On Earth, the weight of 1 kilogram (Kg) is 9,8 Newtons (N).
That said, the bending test is actually important since the more a material can bend, the more it's supposed to absorb the energy of an impact by...bending and vibrating.
And apparently, iPhones haven't been using Gorilla glass since 4.
There have been rumors that Apple has turned to Asahi instead. But like many Apple rumors, this is unsubstantiated.
Corning itself issued a profits warning a couple of months ago, attributing the problem in part to a major Korean customer who first strong-armed Corning into substantial price reduction and then reneged on a substantial order. This could be Samsung cutting its losses on its tablet business, or Samsung switching to a different supplier on orders from Apple.
Again, no direct evidence linking Apple and Corning, or breaking links between them.
There have been rumors that GG is used in Apple notebooks. I don't think these have been substantiated either.
It's because pounds have been used in several scientific and engineering systems of units and as an informal unit for a long time, and so all of the opinions have some claim to be correct. We are actually debating current usage and notation (I think), and that is where we don't all agree. I apologize for the distraction from the topic at hand.
Well about that I wouldn't know since I studied in France so it was all easy for us, no conversions and fortunately no pounds!
I don't even know how much a pound is and I don't want to know!:P
^^This.
I usually tend to understand pound-mass when I say pound, much like majjo has pointed out. The reason for this is simple: when I buy a pound of apples at the market, I expect 453.59237 grams of apples, not 4.44822162 newtons of apples. How that is being measured is immaterial to me, as long as I'm not getting ripped off.
Ohhh, but you are actually getting that much in pounds, yes the force of the Apples! The number derives strictly from the force the fully laden basket of Apples is applying to the scale. The force or weight weight of your apples is intrinsically the local force of Earth gravity and Apple gravity mutually attracting each other.
The mass of the Apples is their physical property independent of the effects of a local gravity well. Pounds or lbs is a force that intrinsically incorporates the gravitational attraction of the earth. Non-Earth vertical force scales can be calibrated to read properly in the vertical and then the force in pounds can be measured in directions other than Earth vertical.
So yes, pounds is a unit of force, a derived unit of force to take a quasi SI view of it, but nonetheless a unit of force.
And just the same pounds is a unit of mass, a sloppy nasty one, but yes a unit of mass as has been argued at length in previous posts.
Bottom line is the usage is very context dependent and that potential ball of confusion was a reason things like the SI system were developed in the first place.