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. 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.
Water at ultra high velocity wasn't measured at your mohs scale reading. At the speeds used for cutter jets the incompressibility properties act totally differently than slowly poking the top of a glass of water with a calibrated stylus.
No, under like conditions (keys in a pocket constitute like conditions) a softer material will not scratch a harder one.
Impurities will tend to blur that line a little, but you still have to have harder impurities than the material you are scratching. Maybe it wasn't the keys, but some quartz containing sand in your pocket that your keys provided an opposing hard surface to push against?
Try this. drop an iphone on asphalt/concrete from 1 meter. Ok it _might survive_. Now drop it on either side on a rhine gravel road, eg. 16-32mm grainsize. It will allmost 100% shure kill the glass guaranteed!! Or just the pavement edge or some other unregular piece of tough metal thats on the floor etc,. you get the picture. I dont care about bending i care about there wouldnt be glass on the backside or past the edges. I might use my iphone without a silicone skin for once.
Now try that with a 1mm thick similar piece of normal or tempered glass or polycarbonate. The regular or even tempered glass will be utterly destroyed. The polycarbonate will get scratches in it almost before it hits the ground. Let it touch fabric that has dust in it and it will swirl and cloud easily.
Gorilla glass is AMAZING stuff. You have to have nearly quarter inch thick tempered glass before you get similar drop strengths, and then the glass is nearly as heavy as the rest of the device. So you get to carry an easily scratched brick that will be a little better on corner impact resistance. How many people would buy that?
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'.
Actually, the article looks like it has, let me count them.... 23 sources. And, many come straight from the National Bureau of Standards.
The old adage that WIkipedia is not a valid source discourse only needs to be mentioned for when you're writing your occasional middle school book report. For many fields, especially in the hard sciences, Wikipedia is actively maintained and well updated. And has faaaaaaaaaarrrrrr more articles than your flimsy old Funk & Wagnalls.
My iPhone 4 fell 3 feet from my pocket and the screen completely shattered. My iPhone 4S screen came in contact with my keys in my pocket and now has a permanent scratch across it. In real-world conditions Gorilla Glass is extremely fragile. All these claims of strength are a bunch of B.S.
That doesn't mean much. My phone dropped from six feet and is fine. A lot depends on the angle of impact, and what the phone contacts on impact. Here is a pretty through test of the phone.
As a non imperial units user, I thought that pound was only a mass unit. I quick internet search showed me that there are two pound units...
As a reminder to anyone, mass and weight are two distinct concepts in physics. As in theory inertial mass and gravitational mass are two distinct things.
As a non imperial units user, I thought that pound was only a mass unit. I quick internet search showed me that there are two pound units...
As a reminder to anyone, mass and weight are two distinct concepts in physics. As in theory inertial mass and gravitational mass are two distinct things.
Not to continue the pointless quibbling over units, but the practical distinction is really between mass and force. What we commonly call "weight" is the force due to gravity here on the surface of the Earth. Only physics instructors (and other pedants :-) ever really care about the distinction between mass and weight -- in the likely event you're confined to the Earth's surface, they're practically identical. Force as a general concept, on the other hand, is easily distinguished from mass.
On Earth, the weight of 1 kilogram (Kg) is 9,8 Newtons (N).
That depends where you are on the Earth. For example at the equator, on the top of a mountain you would weigh slightly less due to centrifugal force being greater than, let's say, The North Pole. Also the Earth's gravitational lines of force are not an exact vector pointing to the center of the Earth either. That also varies depending on several factors including latitude, altitude, the time of year and the position of the moon. I mean, we could be talking nearly several grams of difference if you want to get technical about it.
I must say you have a grip of steal if you have never dropped it on any hard surface. 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... No I havent dropped my iphone 4 without my silicone on but those that buy it as their first iphone maybe shocked if their not told about the fact.
The first iPhone I bought I dropped it face down from about 18 inches while getting out of my car. It hit a rock and shattered the whole face. I had only had the phone 3 days. The Apple employee felt bad for me and replaced it for free (I buy a lot of apple products from the same apple store). It occured to me a case wouldn't have prevented that damage. I don't use a case because it helps remind me to take care of the phone. The only people I know that have dropped their phone did it while opening a door or trying to hold something else in the same hand. I never do that. I always put the phone in my pocket with the screen facing in and I never put other objects in the same pocket. Follow those three rules and you won't need a case and you'll never scratch or drop your phone.
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.
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.
You may be right, which is why I paused to think. However, the link you provided doesn't answer the question. It only discusses that harder materials scratch softer materials. We all know that. The question is whether a softer material can scratch a harder material. For example, can a sharp soft material scratch the planar surface of a harder material. Clearly at some amount of force it can. At the point of atom bombardment, soft materials can clearly scratch a harder material. Maybe that isn't considered a scratch?? Fair enough. I'm just trying to figure out why I have a couple of micro scratches in the back of my iphone. If a softer material really can't scratch a harder material (despite being sharp and a force being applied) then it must be a small rock or piece of sand in my pocket that made a scratch.
LOL with regard to your enlightenment about water not having a mohs hardness. No Shit.
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...
I sometimes use our ottoman (footstool) as a desk. I will then sometimes charge my iPhone via the usb port on the unibody macbook to charge my iPhone. With kids and pets running around sometimes the computer gets bumped or nudged and it slides up and over the phones screen. I believe that the anodized coating on the Macbook or the Apple wireless keyboard is hard enough to scratch the gorilla glass.
That depends where you are on the Earth. For example at the equator, on the top of a mountain you would weigh slightly less due to centrifugal force being greater than, let's say, The North Pole. Also the Earth's gravitational lines of force are not an exact vector pointing to the center of the Earth either. That also varies depending on several factors including latitude, altitude, the time of year and the position of the moon. I mean, we could be talking nearly several grams of difference if you want to get technical about it.
Not to forget that it's 9.81 m/s^2 in the acceleration assuming freefall.
That depends where you are on the Earth. For example at the equator, on the top of a mountain you would weigh slightly less due to centrifugal force being greater than, let's say, The North Pole. Also the Earth's gravitational lines of force are not an exact vector pointing to the center of the Earth either. That also varies depending on several factors including latitude, altitude, the time of year and the position of the moon. I mean, we could be talking nearly several grams of difference if you want to get technical about it.
Yep.
I'm thinking of an infomercial advertising a guaranteed, foolproof weight loss method. For $10,000, I'll send them a ticket to the equator.
This CES feels weak. Too many companies playing catchup to Apple. The most interesting thing is an advancement on fraking glass. Glass!
I thought Intel actually getting closer to shipping a viable (not necessarily competitive) x86 SoC for smartphones and tablets is some pretty big news. And they got a couple of big name suckers (Moto and Lenovo) to make some phones for them, running an x86 version of Android.
If they can compete, it could be a very interesting thing. The half-life on this thing has been a long long time coming, and it's still at least 6 months away.
I thought Intel actually getting closer to shipping a viable (not necessarily competitive) x86 SoC for smartphones and tablets is some pretty big news. And they got a couple of big name suckers (Moto and Lenovo) to make some phones for them, running an x86 version of Android.
If they can compete, it could be a very interesting thing. The half-life on this thing has been a long long time coming, and it's still at least 6 months away.
I'm not betting on that until we start seeing some real devices. Getting some partners is okay but if Intel really has made their architecture mobile we'll see vendors move from ARM willingly and in droves.
Comments
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. 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.
Water at ultra high velocity wasn't measured at your mohs scale reading. At the speeds used for cutter jets the incompressibility properties act totally differently than slowly poking the top of a glass of water with a calibrated stylus.
No, under like conditions (keys in a pocket constitute like conditions) a softer material will not scratch a harder one.
Impurities will tend to blur that line a little, but you still have to have harder impurities than the material you are scratching. Maybe it wasn't the keys, but some quartz containing sand in your pocket that your keys provided an opposing hard surface to push against?
Try this. drop an iphone on asphalt/concrete from 1 meter. Ok it _might survive_. Now drop it on either side on a rhine gravel road, eg. 16-32mm grainsize. It will allmost 100% shure kill the glass guaranteed!! Or just the pavement edge or some other unregular piece of tough metal thats on the floor etc,. you get the picture. I dont care about bending i care about there wouldnt be glass on the backside or past the edges. I might use my iphone without a silicone skin for once.
Now try that with a 1mm thick similar piece of normal or tempered glass or polycarbonate. The regular or even tempered glass will be utterly destroyed. The polycarbonate will get scratches in it almost before it hits the ground. Let it touch fabric that has dust in it and it will swirl and cloud easily.
Gorilla glass is AMAZING stuff. You have to have nearly quarter inch thick tempered glass before you get similar drop strengths, and then the glass is nearly as heavy as the rest of the device. So you get to carry an easily scratched brick that will be a little better on corner impact resistance. How many people would buy that?
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'.
Actually, the article looks like it has, let me count them.... 23 sources. And, many come straight from the National Bureau of Standards.
The old adage that WIkipedia is not a valid source discourse only needs to be mentioned for when you're writing your occasional middle school book report. For many fields, especially in the hard sciences, Wikipedia is actively maintained and well updated. And has faaaaaaaaaarrrrrr more articles than your flimsy old Funk & Wagnalls.
According to Wikipedia, slugs rarely exceed about 4 oz.
A land slug or a sea slug?
A land slug or a sea slug?
Land.
Pounds are units of mass, not force
You make me sad -_-
My iPhone 4 fell 3 feet from my pocket and the screen completely shattered. My iPhone 4S screen came in contact with my keys in my pocket and now has a permanent scratch across it. In real-world conditions Gorilla Glass is extremely fragile. All these claims of strength are a bunch of B.S.
That doesn't mean much. My phone dropped from six feet and is fine. A lot depends on the angle of impact, and what the phone contacts on impact. Here is a pretty through test of the phone.
the true test is putting it into your back pocket and then sitting down on a hard surface. If it does not break it's good...
Even better, will it blend.
You make me sad -_-
As a non imperial units user, I thought that pound was only a mass unit. I quick internet search showed me that there are two pound units...
As a reminder to anyone, mass and weight are two distinct concepts in physics. As in theory inertial mass and gravitational mass are two distinct things.
As a non imperial units user, I thought that pound was only a mass unit. I quick internet search showed me that there are two pound units...
As a reminder to anyone, mass and weight are two distinct concepts in physics. As in theory inertial mass and gravitational mass are two distinct things.
Not to continue the pointless quibbling over units, but the practical distinction is really between mass and force. What we commonly call "weight" is the force due to gravity here on the surface of the Earth. Only physics instructors (and other pedants :-) ever really care about the distinction between mass and weight -- in the likely event you're confined to the Earth's surface, they're practically identical. Force as a general concept, on the other hand, is easily distinguished from mass.
On Earth, the weight of 1 kilogram (Kg) is 9,8 Newtons (N).
That depends where you are on the Earth. For example at the equator, on the top of a mountain you would weigh slightly less due to centrifugal force being greater than, let's say, The North Pole. Also the Earth's gravitational lines of force are not an exact vector pointing to the center of the Earth either. That also varies depending on several factors including latitude, altitude, the time of year and the position of the moon. I mean, we could be talking nearly several grams of difference if you want to get technical about it.
Bonus question: How fast much you throw a Fig Newton cookie to achieve one Newton?
I must say you have a grip of steal if you have never dropped it on any hard surface. 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... No I havent dropped my iphone 4 without my silicone on but those that buy it as their first iphone maybe shocked if their not told about the fact.
The first iPhone I bought I dropped it face down from about 18 inches while getting out of my car. It hit a rock and shattered the whole face. I had only had the phone 3 days. The Apple employee felt bad for me and replaced it for free (I buy a lot of apple products from the same apple store). It occured to me a case wouldn't have prevented that damage. I don't use a case because it helps remind me to take care of the phone. The only people I know that have dropped their phone did it while opening a door or trying to hold something else in the same hand. I never do that. I always put the phone in my pocket with the screen facing in and I never put other objects in the same pocket. Follow those three rules and you won't need a case and you'll never scratch or drop your phone.
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
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.
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.
You may be right, which is why I paused to think. However, the link you provided doesn't answer the question. It only discusses that harder materials scratch softer materials. We all know that. The question is whether a softer material can scratch a harder material. For example, can a sharp soft material scratch the planar surface of a harder material. Clearly at some amount of force it can. At the point of atom bombardment, soft materials can clearly scratch a harder material. Maybe that isn't considered a scratch?? Fair enough. I'm just trying to figure out why I have a couple of micro scratches in the back of my iphone. If a softer material really can't scratch a harder material (despite being sharp and a force being applied) then it must be a small rock or piece of sand in my pocket that made a scratch.
LOL with regard to your enlightenment about water not having a mohs hardness. No Shit.
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...
I sometimes use our ottoman (footstool) as a desk. I will then sometimes charge my iPhone via the usb port on the unibody macbook to charge my iPhone. With kids and pets running around sometimes the computer gets bumped or nudged and it slides up and over the phones screen. I believe that the anodized coating on the Macbook or the Apple wireless keyboard is hard enough to scratch the gorilla glass.
That depends where you are on the Earth. For example at the equator, on the top of a mountain you would weigh slightly less due to centrifugal force being greater than, let's say, The North Pole. Also the Earth's gravitational lines of force are not an exact vector pointing to the center of the Earth either. That also varies depending on several factors including latitude, altitude, the time of year and the position of the moon. I mean, we could be talking nearly several grams of difference if you want to get technical about it.
Not to forget that it's 9.81 m/s^2 in the acceleration assuming freefall.
That depends where you are on the Earth. For example at the equator, on the top of a mountain you would weigh slightly less due to centrifugal force being greater than, let's say, The North Pole. Also the Earth's gravitational lines of force are not an exact vector pointing to the center of the Earth either. That also varies depending on several factors including latitude, altitude, the time of year and the position of the moon. I mean, we could be talking nearly several grams of difference if you want to get technical about it.
Yep.
I'm thinking of an infomercial advertising a guaranteed, foolproof weight loss method. For $10,000, I'll send them a ticket to the equator.
This CES feels weak. Too many companies playing catchup to Apple. The most interesting thing is an advancement on fraking glass. Glass!
I thought Intel actually getting closer to shipping a viable (not necessarily competitive) x86 SoC for smartphones and tablets is some pretty big news. And they got a couple of big name suckers (Moto and Lenovo) to make some phones for them, running an x86 version of Android.
If they can compete, it could be a very interesting thing. The half-life on this thing has been a long long time coming, and it's still at least 6 months away.
I thought Intel actually getting closer to shipping a viable (not necessarily competitive) x86 SoC for smartphones and tablets is some pretty big news. And they got a couple of big name suckers (Moto and Lenovo) to make some phones for them, running an x86 version of Android.
If they can compete, it could be a very interesting thing. The half-life on this thing has been a long long time coming, and it's still at least 6 months away.
I'm not betting on that until we start seeing some real devices. Getting some partners is okay but if Intel really has made their architecture mobile we'll see vendors move from ARM willingly and in droves.