Dec 15, 2022 20:00:00

Verify with slow motion video which is faster, `` speed of breaking glass '' or `` speed of bullet ''

When thin glass is broken, even if there is just one point of impact, the crack spreads to the whole in an instant so that it cannot be seen by the human eye, and it breaks into pieces.

The Slow Mo Guys , who has shot a number of slow motion videos, has released a video comparing the speed of breaking this glass with the speed of a bullet.

Does Glass Break Faster than a Bullet?-YouTube


Gab (left) and Dan (right) from The Slow Mo Guys, a popular YouTube channel with over 14 million subscribers.

Investigate which is faster, 'glass breaking speed' or 'bullet speed'. Video footage of each situation is shown below.

Then, if you shoot a movie of shooting a bullet, the lower half is trimmed, and if you shoot a movie of breaking glass, the upper half is trimmed.

By synthesizing the two videos, you can complete a video that looks as if you shot ``shooting a bullet'' and ``breaking glass'' at the same time. Now let's see which one is faster.

The Phantom high-speed camera ' TMX 7510 ' was used for shooting. It uses the industry's first back-illuminated sensor, and if the resolution is 1280 x 800 pixels, it will be possible to shoot at 76,000 fps.

So, first prepare a thin glass with a width of 6 feet (about 1.8 meters) marked every 1 foot (about 30 cm).

Warning sign 'Don't experiment at home!'

Then break the glass with pliers. In an instant, the whole glass shattered.

Next, prepare a handgun.

and fired. Ordinary cameras cannot even capture bullets.

However, if you capture the moment of firing with a high-speed camera, it will be as follows.

First of all, black smoke blows out from the muzzle.

And bullets flew out with fire.

With a slow motion video of 80,000 fps, you can clearly see how the bullet flies.

Then break the glass.

The impact is transmitted to the surface of the glass from the tip of the pliers on the right end.

Two people checking the video they shot on the spot. Even without synthesizing the video, it seems that the speed at which the glass breaks is faster.

Below is a video of the actual composition. The videos shot at the same frame rate are combined so that the bullet and the crack in the glass surface are on the rightmost wooden stick at the same time.

The crack in the glass traveled almost six feet before the bullet traveled two feet.

When calculating the speed based on the image, it turned out that the speed of the bullet was 768 mph (343 meters per second), while the breaking speed of the glass was 3214 mph (1436 meters per second), which was more than four times faster. . Since the speed of sound in the atmosphere is about 340 meters per second, even a bullet will exceed the speed of sound. On the other hand, since the vibration transmitted through the glass is much faster than the speed of sound in the atmosphere, the breaking speed of the glass is much faster than the bullet.

Next, fire the handgun behind the glass.

And parin the glass.

This time it is a super slow motion video of 200,000 fps.

A crack in the glass occurred around the point where the bullet almost crossed the screen.

The timing to reach the left edge of the screen is the same. There is a difference between the speed of the bullet and the speed at which the glass breaks.