Yes, that’s the video. At the 5:07 mark you see a spreadsheet. In column G he’s got speed of bullet - 3100 fps 0r 1033.3 yards per second. Then he’s got the speed of sound at 1152 fps or 384 yards per second. So far so good. But he then subtracts one from the other and gets the difference of 649.3 yards per second.
You can see in cell C2 where he’s taken 643.3 yards per second times .22 seconds and gotten 141.5 yards.
643.3 yards per second isn’t a number that’s applicable. The only times the difference in speed is going to make sense is in word problems like “A horse runs at 40 mph and a dog runs at 25 mph. How much further does a horse run if they both run for 1 hour?”
But here you don’t have the the bullet and the sound of the bullet traveling for the same amount of time. They are traveling the same DISTANCE, not the same amount of time.
You need to assume the time for bullet to travel is t1, and time for the sound of the bullet is t2. t2 minus t1 is 0.22
You have to set up equations for
- how long it takes a bullet travels to travel the distance (t1 = distance / speed of bullet)
- how long it takes the sound of the bullet to reach the microphone (t2 = distance / 1152 fps)
We know that t2 - t1 = 0.22
We don’t have enough info to solve those equation yet. We have to guess what the average bullet velocity is, since we don’t know the exact make of rifle and type of bullets. The answer will only be approximate, since that velocity is a guess.
The poster of that video is using 3100 fps.
In that case t1 = distance/3100.
The answer works out to be 403.3 feet (it’s nowhere near as exact as that sounds, of course)
t1 = .1301 seconds
t2 = .3501 seconds
difference is 0.220 seconds
I stunk as a graduate teaching assistant, but I hope that makes a little sense.