class 27

# class 27 - • Slope of x(t is velocity and 3.880 m/s which...

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1 ENGR 111 Fall, 2009 Class 27 ~ Week 14

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2 Video Data ~ Team 13 Why is this video reversed?
3 Video Formats Most “standard” video is 30 (or 25) frames/sec. It may be interlaced. Full Frame Interlaced: A Field Interlaced: B Field

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4 • Save individual frames with time stamps. • De-interlace A and B fields if necessary. • Locate key points in each frame. • Track the movement of the key points. • Generate x(t) and y(t) data ~ position/time. • Calculate vx(t) and vy(t) ~ 1st derivative of position/time. • Calculate ax(t) and ay(t) ~ 2nd derivative of position/time. Extracting Data from Video
5 Single Frame with a Key Point Center of right front wheel

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6 1 2 3 4 5 6 Floor Key points at 0.077 second intervals
7 Key point locations

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8 If the drag is small: • The x-component of velocity should be constant.

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Unformatted text preview: • Slope of x(t) is velocity, and 3.880 m/s, which is lower than we measured. • y(t) should be parabolic. An equation that approximates this is a second order trendline in Excel: Position 0.000 0.200 0.400 0.600 0.800 1.000 1.200 1.400 0.000 0.100 0.200 0.300 0.400 time (s) Distance (m) x (m) y (m) y t ( ) 4.7123 − t 2 ⋅ 0.0494 t ⋅ − 0.5568 + This can be compared with the theoretical equation in vacuum: y 0.56 m ⋅ 1 2 g ⋅ t 2 ⋅ − = 1 2 g ⋅ 4.903 m s 2 = where: Analysis 9 y(t) least sq. y(t) theoretical t x(t) measured (sec) (m) (m) (m) 10 RAT 27-1 11 3 minutes: It would have been easier to analyze the video if there had been several other items in the field of view. Name three. RAT 27-1...
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## This note was uploaded on 04/04/2011 for the course ENGR 111 taught by Professor Walker during the Fall '07 term at Texas A&M.

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class 27 - • Slope of x(t is velocity and 3.880 m/s which...

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