Biomechanics

• What is the standard video recording frequency mentioned?

  50 Hz
• What are the two types of video mentioned for recording kinematic information?

  Standard video and high-speed video
• What are the key components to consider when recording kinematic information?

  • CCD/CMOS: 3 chip vs 1 chip
  • Recording formats
  • Focal length
  • Shutter speed
  • Aperture/depth of field
  • Lens distortion
  • Set up: perspective/parallax error
  • Scaling
• What does CCD stand for?

  Charge-Coupled Device
• What are the recording formats and their resolutions mentioned?

  • VHS: 240 x 576 (0.14 MP)
  • MiniDV: 720 x 480 (0.35 MP)
  • iPhone XS: 12 MP photo, 8 MP video
• What are the displaying formats and their resolutions mentioned?

  • VGA: 640 x 480
  • HDMI 1.0: 1920 x 1200
  • 4K: 3840 x 2160
• What is the importance of field of view in recording?

  It should contain all the action of interest
• What is shutter speed in video recording?

  Time sensor is exposed to light
• At what frequency does a video camera operate?

  50 Hz (50 fps)
• What happens when the shutter speed is too low?

  Motion blur may occur
• How does aperture affect exposure?

  Smaller f-number means larger aperture
• What is the relationship between aperture and depth of field?

  Depth of field increases as aperture decreases
• What should be ensured when setting up for a large depth of view?

  Additional lighting may be required
• What types of lens distortion are mentioned?

  • Pin cushion distortion
  • Barrel distortion
• What are the key considerations for 2D analysis in video recording?

  • One camera
  • Planar movements
  • Camera perpendicular to movement plane
  • Scale information
• What are the setup requirements for a video camera?

  • Field of view
  • Focusing (avoid auto focus)
  • Shutter speed
  • Aperture
  • Lighting (indoor/outdoor)
  • Background
  • Scale information
• How is scale information calculated in video analysis?

  Using known dimensions in the plane of motion
• What is the formula for calculating scale factor?

  Pixels per meter
• What is perspective error in video analysis?

  Calibration object not in the plane of movement
• How can parallax error be reduced?

  By placing the camera perpendicular to movement
• What are the summary points for effective video recording?

  • Camera perpendicular to movement
  • Field of view and focal length
  • Background considerations
  • Focusing (avoid auto focus)
  • Shutter speed for exposure
  • Aperture for exposure
  • Scale information
  • Lighting (indoor/outdoor)
• What is inertia?

  Reluctance of a body to change motion
• What is mass measured in?

  Kilograms (kg)
• How does mass relate to inertia?

  Large mass results in large inertia
• What is the formula for linear momentum?

  Linear momentum = mass x velocity
• What is the horizontal linear momentum of a 70 kg mass moving at 5 m/s?

  350 kg.m.s-1
• What is force measured in?

  Newtons (N)
• How can a force be defined?

  As a pushing or pulling action
• What acceleration does a force of 1 N produce on a 1 kg mass?

  1 m.s-2
• What does linear kinetics study?

  Motion and its causes, like forces
• What are internal forces?

  Forces like muscle and joint forces
• What are external forces?

  Forces like gravity and air drag
• What does Newton's First Law state?

  An object remains at rest or constant motion
• Why is Newton's First Law difficult to demonstrate on Earth?

  There is always a force acting on a body
• What is sometimes referred to as the law of inertia?

  Newton's First Law
• What does Newton's Second Law describe?

  Rate of change of momentum is proportional to force
• What is the formula for Newton's Second Law?

  F = ma
• What does Newton's Third Law state?

  For every action, there is an equal reaction
• What is force considered as?

  A vector quantity with magnitude and direction
• What is weight defined as?

  The force due to gravity (mg)