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Think the case it was in would have changed things a bit?Well 6 feet is a lot different than 500 feet or 13,500 feet
For fun or people's general information if they are curious....
If I ran my calculations correctly, assuming:
- Weight of iPhone 4 is 137 grams
- Drag Coefficient is about .6. Without experimentation, there's be no way to actually know this, but assuming the iPhone 4 is tumbling randomly, it would be between somewhere from worst case (1.28 or so) to a flat plate parallel to the air flow (.01).
- Cross sectional area is .006785 square meters
- Dropped from 13,500 feet
Terminal Velocity of 28.3464 m/s = 63.4 miles per hour when it hit the ground.
Of course, I'm ignoring the slight change in air density as the iPhone came closer to Earth and the fact that the drag coefficient is constantly variable assuming a tumbling iPhone, but it's quick none-the-less.
As further fun facts, it would take a bit over 3 seconds to reach this speed. In fact, the quickest the iPhone 4 could reach this terminal velocity is 2.889 seconds (if we assume the acceleration of the iPhone is 9.81 m/s^2, which is isn't, because this is in pure free fall without drag).
(In all honesty it depends on the acceleration of gravity based on this terminal velocity. It would take 4.586 seconds assuming an acceleration of 6.18 m/s^2, which is assuming the iPhone is a particle and the viscosity is 1.78e-5 kg/m*second at 15 degrees Celsius. Again, the viscosity and density of air will change as the iPhone drops meaning that the iPhone's acceleration due to gravity will change, which in combination with drag force, means the terminal velocity of the iPhone will change as well as it falls to the Earth. Main point being here is the phone was moving pretty quickly; however, it would take in a perfect world 41 meters to reach terminal velocity (assuming initial velocity of 0, acceleration due to gravity perfect at 9.81 m/s^2, time of 2.889 seconds to reach terminal velocity, and no drag force). Real world, of course, would take a further distance, 65 meters or so.)
(Finally, another fun fact: depending on how the skydiver was oriented falling to the Earth, the skydiver would probably hit the ground first were it not for parachutes; terminal velocity for humans can be up to 120mph, which means you'd see your iPhone "falling upwards" as you fell to Earth.)
Equations for those curious: NASA
BTW, Anyone ever toss a 9000 on the counter or a desk? Now that is solid.Last edited by olblueyez; 07-23-11 at 09:38 AM.
07-23-11 09:34 AM - If you run the calculations yourself, you'll see that calculations were all performed in metric and converted at the end into imperial for people who use imperial units. Further, I was just stating some of the constants in imperial from the article, but made sure they were converted when running my calculations.With the quoted mix of metric and imperial units for a single calculation it seems someone else missed a fundamental lesson too.
Check it yourself I won't say I'm perfect, but I do make sure I run straight metric when doing Physics calculations.
Possibly. What happens when the phone hits the ground is the phone pushing against the Earth with some normal Force (in this case, all coming from the gravitational pull of Earth), and when it hits the ground, the Earth responds with an equal but opposite force. Now, some of the energy transfer here is absorbed by the ground conditions, some transfered as heat, and some transfered back into kinetic energy for the phone.
That being said, with the case on the phone, the phone would transfer energy to the case, then to the ground and vice versa on the way back up. That being said, it means you have a middle man that can, essentially, help diffuse or absorb some of the energy from going back to the phone.
The main question here is how much energy or Force does the case cushion, and would it have made a difference? I couldn't tell you....experimentation would be the best bet real world, or knowing the case composition could lead to advanced calculations on energy transfer, but I'll admit that's a little out of my area of expertise in Physics.
See my comment above about energy transfer. On the one hand, concrete is not going to "dampen" the fall compared to, say, grass; however, you'll find that the energy of the fall from 13,500 feet is much greater due to the speeds involved, so you can't make that assumption right away
Yep yep, exactly. That's why the calculations I did are rough: there's no way to know the exact air density at the time nor was I adjusting for that change or force of gravity.
As you said, many factors. The type of case would affect the damage done to the phone obviously, and also I'm not sure how much help the screen will do at that sort of energy and force levels on impact. It could be nothing, or it could make all the difference....
And, the phone fell on a roof which could be sloped effectively opening up the possibility that the phone hit it on an angle making the impact less severe.
Trust me, I'm doing a PhD in physics, I know this stuff.
I think we can all agree that Blackberries are generally more resilient to impact than iphones. The case helped to keep the phone together, but the glass would have shattered regardless.
Now, the storm with:
a screen that absorbs impact in three dimensions....
a lock and mute button that can absorb some pushing at the top
THAT would be interesting to see if the screen shatters....although tests like this depend on too many factors. I would say that without a case, the phone is toast, but with any case on, the phone would be useable but damaged but there's a good chance the screen would be fine because it moves to absorb the shock.
So to test this theory, we'll need I think 3 iPhone 4s, 1 iPhone 4 case (hard shell) and one iPhone 4 case (soft shell), 3 BlackBerry Storms, 1 hard case, 1 soft case, a private plane, a certified skydiver, and a $.99 G-Force measuring app07-28-11 02:06 AM
