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Thread: Video of Car Driving By Camera, How Fast is it Going?

  1. #1 Video of Car Driving By Camera, How Fast is it Going? 
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    Hi,

    I'm curious to know, based on the video below, if anyone can conclusively say how fast the car driving by is going? Would you need additional information?

    Video of Car Driving By Camera, How Fast is it Going?



    Here's the infographic, is this enough to solve how fast this car is going (in mph)?
    http://cl.ly/PqpJ


    Last edited by drswank; June 24th, 2013 at 03:13 PM. Reason: add file
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  3. #2  
    Forum Radioactive Isotope cosmictraveler's Avatar
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    It took about 1 second to travel what looks like about 50 feet so with that information you could tell but the exact distance isn't known so there could be a little difference.


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  4. #3  
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    Quote Originally Posted by cosmictraveler View Post
    It took about 1 second to travel what looks like about 50 feet so with that information you could tell but the exact distance isn't known so there could be a little difference.
    So maybe if I got exact distance traveled, and determined how many frames it took for the car to travel that distance... would that be enough?
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  5. #4  
    Genius Duck Moderator Dywyddyr's Avatar
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    Unless you know the frame rate of the camera you can't tell the time in a film accurately - i.e. what is shown may not be in synch with reality.
    Are we getting into conspiracy theory here?
    FBI assassinations?
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  6. #5  
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    Quote Originally Posted by Dywyddyr View Post
    Unless you know the frame rate of the camera you can't tell the time in a film accurately - i.e. what is shown may not be in synch with reality.
    Are we getting into conspiracy theory here?
    FBI assassinations?
    Heh, I'm just curious to know how fast he was driving, and if determined, can determine the speed at which the tree was hit, based on car-to-tree damage. I'm trying to understand what speed he may have hit the tree at. If the speed determined by the camera here is XXmph, and based on past car accidents where certain amount of tree damage was done to the vehicle based on an equivalent speed... that's what I'm trying to understand. It's just piqued my interest is all.
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  7. #6  
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    Quote Originally Posted by Dywyddyr View Post
    Unless you know the frame rate of the camera you can't tell the time in a film accurately - i.e. what is shown may not be in synch with reality.
    If I found out what the framerate that camera is filming out (more than likely 30fps), then that would establish a good reference.
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  8. #7  
    Forum Radioactive Isotope cosmictraveler's Avatar
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    The biggest problem here is that the car RAN THE RED LIGHT!!
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  9. #8  
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    Quote Originally Posted by cosmictraveler View Post
    The biggest problem here is that the car RAN THE RED LIGHT!!
    indeed he did Im going to drive down there and measure distance. The camera was filming at 30fps.
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    Genius Duck Moderator Dywyddyr's Avatar
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    Oops: addendum - then you'd also have to check/verify that the playback is done at that speed.
    (I don't know much about filming/ video, so I don't know* if it's possible to play back at a different speed than it was recorded).

    * Although I'd be surprised if it wasn't.

    You don't need to measure on-site though.
    If you know the car make/ model then you can use the known length of the vehicle to get distances covered (how long to traverse its own length for example) - that obviates any problems with establishing other data points.
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  11. #10  
    has lost interest seagypsy's Avatar
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    if he knows the frame rate he wouldn't have to worry about playback speed as he would just count how many frames it took for hte car to travel the distance. If one frame represents 1 second for instance(which would look really choppy) then he would just count each frame as one second of time. but in this case of 30fps. then he would have to count the frames and divide by 30 to get the number of seconds to go the distance he has determined, such as car length or distance from corner to street light or whatever.
    Speaking badly about people after they are gone and jumping on the bash the band wagon must do very well for a low self-esteem.
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  13. #12  
    Genius Duck Moderator Dywyddyr's Avatar
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    Quote Originally Posted by seagypsy View Post
    if he knows the frame rate he wouldn't have to worry about playback speed as he would just count how many frames it took for hte car to travel the distance. If one frame represents 1 second for instance(which would look really choppy) then he would just count each frame as one second of time. but in this case of 30fps. then he would have to count the frames and divide by 30 to get the number of seconds to go the distance he has determined, such as car length or distance from corner to street light or whatever.
    But surely to do that you need a copy of the film itself to examine it frame by frame?
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  14. #13  
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    Car is 2013 Mercedes C250.
    Length Dimensions: 180.8 inches (15.07 feet)

    I'll download the video tomorrow, count frames, and post an infographic with length of overall distance traveled.
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  15. #14  
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    added infographic with precise frame count, car dimensions, path traveled in milliseconds.

    Here's photo:
    hastings-infographic.png

    Here's raw data:

    Video Framerate = 30fps.
    Frame Count from Entry to Exit = 19 Frames
    Time of Travel = 630ms

    Car Dimensions = 180.7 inches (15.6 feet)
    Distance of Travel = 903.5 inches (75.3 feet)

    Therefore, the car approximately traveled 903.5 inches in roughly 630 milliseconds.

    How fast was this car going (in mph)?
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    (903.5/.63) (inch per second) = 81.4844877 miles per hour
    https://www.google.com/search?q=903....w=1066&bih=488
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