1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Physical speed of Edgerton's Trinity spool?

  1. May 2, 2012 #1
    I found a website which claimed that 3500 feet of 35mm film was shooting at a maximum speed of 10600000 frames per second, to catch the first millionths of a second after the trinity explosion.

    I have an issue with how in the world this was done. I know that the camera exploded and the film had to be contained, but 10600000 frames per second means it traversed ~37mm 10600000 times every second. This means that the film spool must have been traveling at 894,000 mph! This would have run through the 3500 feet of spool in .0027 seconds! Am I doing these calculations wrong, or is the website wrong, or is the "huge spool of pre-tensioned 35 mm film" not quite as I am envisioning it?
  2. jcsd
  3. May 2, 2012 #2
    This might be posting in the wrong board, so I'll try another spot. This isn't really classical physics so much as it's a general question. Feel free to delete this thread.
  4. May 2, 2012 #3


    User Avatar
    Gold Member

    Do you have a link to that claim? You should be aware that 35mm film was developed as a movie camera film and was only later adapted for use in small canisters for still cameras by the Germans (initially). I have no knowledge of such high-speed movie cameras (in the claim you cited), but I'd love to see some back-up.
  5. May 3, 2012 #4


    User Avatar
    2017 Award

    Staff: Mentor

    Well, moving film material with 900,000mph is not possible (with reasonable methods).

    One odd thing: With 10 million frames per second, every millionths of a second needs some centimeters of film. Therefore, 3500 feet are a bit long to capture "the first millionths of a second".

    However, I am quite sure that they did not use the regular video camera system. For example, you could use a non-moving film, and move an image over it via a rotating mirror or similar systems. This is (relatively) easy to do if you want to film a single line (instead of a 2D image), and with multiple systems you can film several lines at the same time.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook