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Cake day: July 8th, 2023

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  • That was some seriously cringe slogan.

    But how was this ever enough to justify voting for the guy who has no morality, cheats and bullshits his way through everything, selects his entourage based on loyalty over competence, divides the country through purposefully polarizing statements and filed for bankruptcies 6 times, 5 of which were casinos? And that was what we knew before he was elected.

    That’s just showing how superficial a lot of the voter base really is.





  • The standard “ball” bullet used by the Russian military, at least, in the 5.45x39mm is designed to easily tumble once it is inside the target. It is more of an effect of the bullet’s construction and fine tuning of the rifling twist rate than the caliber itself. But it is still supposed to remain stable with the nose pointed forward when traveling to the target. Otherwise it becomes extremely inaccurate and loses its velocity very rapidly, which causes it to fall short.


  • It is keyholing. It happens when as you can see the bullet loses stability and tumbles in the air before hitting the paper sideways. It can be caused by many things. Insufficient rifling twist for the length of the bullet being used is one of them. The bullet hitting the ground or something else before hitting the target is another possibility.

    Either way, it isn’t a desirable thing and indicates that something is wrong. The fact that the PLA members are proudly posting pictures of a bunch of keyholes randomly splattered all over a target like that suggests that they think this is normal and that therefore they don’t know what they’re doing.

    The term “keyholing” is also sometimes erroneously used to refer to when two bullet holes are touching on paper.


  • DaddleDew@lemmy.world
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    9 days ago

    As sound travels through a water layer where the speed through which it travels varies with depth, the sound will tend to refract towards where it is the slowest.

    A layer where temperature decreases as depth increases will refract sound downwards. A layer that has the inverse temperature properties will do the opposite. A layer that is isothermal (where the temperature remains constant as depth changes), will still tend to refract sound upwards because the increase in pressure also increases velocity, although not as strongly as temperature does, which is why temperature differences can easily overcome this effect where the water is not isothermal.

    If you have a layer that refracts sound downwards on top of a layer that refracts sound upwards, you just created a sound channel, which acts as a wave guide in which sound will remain trapped and travel far longer distances horizontally before dissipating.

    Ultimately you can’t really put a number on the required temperature differences because there are many other factors to take into account like how steeply the speed of sound changes, how tall the layer(s) are, what is the frequency of the sound, or how much of it you want to remain “trapped” in the sound channel.


  • DaddleDew@lemmy.world
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    9 days ago

    How well sound propagates through water is highly dependent on the water temperature variations over depth. There can be conditions in which sounds can be trapped between two different horizontal “layers” and travel far greater distances than 80km.