Oct 18, 2018 21:00:00

Why are there many people who smart screens are broken?

If you smartphone users, you should have once experienced that you accidentally dropped the smartphone and cracked the screen. Even if I dropped myself, a movie that physically verifies the moment when the screen of the smartphone breaks can not be thought of as "Why has fallen the screen down ...!?" Is released, and " Why does the screen fall downward? "And" how to cope when it is about to drop out ".

【Physics Engine】 Why is there a lot of people with smart screens broken [Daily Questions] - YouTube

One of the " Murphy's Law " expressing empirical rules and others in humor, "The probability of a dropped bread landing with the butter-coated side down is proportional to the price of the carpet."

In other words, it is a rule of thumb that "anything worse happens" happens.

The influence of butter painted on bread is considered to be quite small, so if you drop it randomly, the probability that the surface coated with butter fell downward should be 50%.

In other words, Murphy's law seems to strongly remember only psychologically bad results.

However, there are people who have verified this physically.

(PDF) and some research verified which side the pan falls down from "drop height", "friction between the bread and the table", "how the center of gravity of the pan goes out" and so on.

As a result, for the butter-coated side to fall upwards ......

It is obvious that the height of the table on which to place the bread must be about 3 meters.

In other words, "When dropping bread from the height of the table used by humans, it will fall with butter face down".

As a result, in the case of bread, it is not "not only bad things are memorized" but "it is highly probable that you physically drop the butter face down."

As in the case of this bread, I would like to verify that the person who seems to be frequent in the town, "Who breaks the screen of the smartphone" is Murphy's law or is it physically broken so often? This is the movie of this time.

For that reason, it is "Height that makes smartphone screen down and easy to fall". Since it is obvious that the probability that the screen cracks when the smartphone is dropped is higher when "the screen fell downwards", we will examine this "height of the smartphone with its screen facing down".

As a condition for verification with the physical engine, the smartphone uses " iPhone 6s ". Size and weight are as indicated, center of gravity is the center of the terminal.

Calculate the angle at which the terminal slides off the hand using iPhone 6s in hand and using the protractor app on iOS. This will roughly calculate the coefficient of friction between the back of the smartphone and the skin.

According to this, it seems that the terminal slipped down when it cant about 18 degrees. From here, it was calculated that the static friction coefficient of the iPhone 6s and the skin is 0.325, and the dynamic friction coefficient is 0.30.

Next, prepare a lot of hands with different heights and try various dropping methods.

Experiment 1

When a smartphone held in the hand falls forward

The angle holding the smartphone in the hand is "30 degrees upward from the horizontal", letting the center of gravity protrude about 1 cm from the finger and drop it.

In other words, it slides down from the hand like this.

That's why I drop it from various heights.

As a result of experiments, it seems that the screen of the smartphone falls downward when the height is 2 meters.

When dropping from the height of 2 to 6.9 meters, the screen of the smartphone faces upwards, and after that the screen falls again downward.

It seems that it can be confirmed even if I actually tried it in reality. Also, trying with smartphones at various angles does not have such a big influence, and in most cases it seems to be "falling with the screen facing down."

Experiment 2

Next, simulate the case where the smartphone held in your hand slides like you slide forward

The angle of the smartphone held in hand when falling to the front is 30 degrees upward from the horizontal. The center of gravity of the smartphone should be directly above the index finger and slide down like a slide above the hand.

On this assumption that the smartphone slides off the palm of your hand, I will drop it again from various heights. Then, even if you drop your smartphone in front, the screen looks pointing downwards depending on the height that people use.

In the case of a height of 2.3 m from the ground, the screen of the smartphone felled so as to face downward.

In Experiment 3, I experimented the case where I dropped it while holding the smartphone screen sideways.

In the case of holding the smartphone sideways, the screen faces downwards up to 1.5 meters in height.

When a person 170 cm tall is standing, the height of holding a smartphone in the hand is roughly 1.1 meters.

As a result of verifying the way of dropping three ways, it is clear that the probability of the screen falling downward is high when humans drop from the height with smartphone in hand. In addition, it seems that the display cracks more easily when falling off the edge of the screen than falling to the ground throughout the screen.

As a result, when a human dropped a smartphone from the hand, the probability that the screen faces downward in any way of falling is high, so the result that "the screen of the smartphone is quite broken" was led .